Scheming in Dimensional Regularization

We consider the most general loop integral that appears in non-relativistic effective field theories with no light particles. The divergences of this integral are in correspondence with simple poles in the space of complex space-time dimensions. Integrals related to the original integral by subtraction of one or more poles in dimensions other than D=4 lead to nonminimal subtraction schemes. Subtraction of all poles in correspondence with ultraviolet divergences of the loop integral leads naturally to a regularization scheme which is precisely equivalent to cutoff regularization. We therefore recover cutoff regularization from dimensional regularization with a nonminimal subtraction scheme. We then discuss the power-counting for non-relativistic effective field theories which arises in these alternative schemes.Comment: 12 pages, additional text in opening section, version to be published in J. Phys.

Dimensional versus cut-off renormalization and the nucleon-nucleon interaction

The role of dimensional regularization is discussed and compared with that of cut-off regularization in some quantum mechanical problems with ultraviolet divergence in two and three dimensions with special emphasis on the nucleon-nucleon interaction. Both types of renormalizations are performed for attractive divergent one- and two-term separable potentials, a divergent tensor potential, and the sum of a delta function and its derivatives. We allow energy-dependent couplings, and determine the form that these couplings should take if equivalence between the two regularization schemes is to be enforced. We also perform renormalization of an attractive separable potential superposed on an analytic divergent potential.Comment: 19 pages + one postscript figur

Building light nuclei from neutrons, protons, and pions

In these lectures I first explain, in a rather basic fashion, the construction of effective field theories. I then discuss some recent developments in the application of such theories to two- and three-nucleon systems.Comment: 54 pages, uses czjphys.cls. Lectures given at 14th Summer School "Understanding the Structure of Hadrons", Prague, July 2001. To appear in Czechoslovak Journal of Physic

Algorithms for learning parsimonious context trees

Parsimonious context trees, PCTs, provide a sparse parameterization of conditional probability distributions. They are particularly powerful for modeling context-specific independencies in sequential discrete data. Learning PCTs from data is computationally hard due to the combinatorial explosion of the space of model structures as the number of predictor variables grows. Under the score-and-search paradigm, the fastest algorithm for finding an optimal PCT, prior to the present work, is based on dynamic programming. While the algorithm can handle small instances fast, it becomes infeasible already when there are half a dozen four-state predictor variables. Here, we show that common scoring functions enable the use of new algorithmic ideas, which can significantly expedite the dynamic programming algorithm on typical data. Specifically, we introduce a memoization technique, which exploits regularities within the predictor variables by equating different contexts associated with the same data subset, and a bound-and-prune technique, which exploits regularities within the response variable by pruning parts of the search space based on score upper bounds. On real-world data from recent applications of PCTs within computational biology the ideas are shown to reduce the traversed search space and the computation time by several orders of magnitude in typical cases.Peer reviewe

Desarrollo de un Hierro Nodular Bainítico para fabricar Piezas de Equipos de la Construcción

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Diretrizes para processo de projeto de fachadas com painéis pré-fabricados de concreto em ambiente BIM

Este artigo expõe as diretrizes para a criação de um processo de elaboração de projetos que utilizam painéis pré-fabricados de fachada, tendo como base o ambiente de Building Information Modeling (BIM). Os painéis pré-fabricados arquitetônicos de concreto (PPAC) foram utilizados como ponto de partida para a estruturação da proposta. A lógica de montagem justifica esta abordagem: assim como no sistema construtivo pré-fabricado, em que as peças são construídas fora do canteiro e chegam a este no momento da montagem, em BIM, os componentes da indústria da Arquitetura, Engenharia e Construção (AEC) são modelados independentemente e inseridos no momento oportuno no modelo. Foram realizados estudos teóricos sobre as características dos PPACs, seguidos de consulta a profissionais experientes do setor, para confirmação da seleção de dados e procedimentos necessários para o projeto. Em seguida, elaboraram-se fluxogramas de orientação para o processo de projeto. Uma simulação do procedimento proposto foi feita com o programa Revit 2013, para validação. A proposta procura auxiliar o projetista a definir os passos de projeto, bem como os dados para a modelagem dos elementos. Ao auxiliar projetistas a conceber projetos utilizando elementos pré-fabricados, procura-se facilitar e estimular seu uso mais frequente no país