Axiomatization and Models of Scientific Theories

In this paper we discuss two approaches to the axiomatization of scien- tific theories in the context of the so called semantic approach, according to which (roughly) a theory can be seen as a class of models. The two approaches are associated respectively to Suppes’ and to da Costa and Chuaqui’s works. We argue that theories can be developed both in a way more akin to the usual mathematical practice (Suppes), in an informal set theoretical environment, writing the set theoretical predicate in the language of set theory itself or, more rigorously (da Costa and Chuaqui), by employing formal languages that help us in writing the postulates to define a class of structures. Both approaches are called internal, for we work within a mathematical framework, here taken to be first-order ZFC. We contrast these approaches with an external one, here discussed briefly. We argue that each one has its strong and weak points, whose discussion is relevant for the philosophical foundations of science

Enraizamento de estacas de mangostão com diferentes concentrações de auxinas.

Ensaio para verificar a possibilidade de obtencao de estacas enraizadas de mangostao sob nebulizacao intermitente de auxinas. Os resultados preliminares indicam a possibilidade de obtencao de mudas de estacas enraizadas de mangostao, embora haja necessidade de ensaios mais elaborados, onde serao estudados os tipos de estacas, epocas e dosagens de fitormonios. Mesmo obtendo-se taxas de enraizamento nao muito altas, o tamanho da muda obtida pelo tratamento com fitormonio equivale a uma muda de um ano proveniente de sementes apomiticas, o que valida os resultados obtidos e corrobora com a continuidade da pesquisa.bitstream/item/89231/1/PA-35.pd

An exact master equation for the system-reservoir dynamics under the strong coupling regime and non-Markovian dynamics

In this paper we present a method to derive an exact master equation for a bosonic system coupled to a set of other bosonic systems, which plays the role of the reservoir, under the strong coupling regime, i.e., without resorting to either the rotating-wave or secular approximations. Working with phase-space distribution functions, we verify that the dynamics are separated in the evolution of its center, which follows classical mechanics, and its shape, which becomes distorted. This is the generalization of a result by Glauber, who stated that coherent states remain coherent under certain circumstances, specifically when the rotating-wave approximation and a zero-temperature reservoir are used. We show that the counter-rotating terms generate fluctuations that distort the vacuum state, much the same as thermal fluctuations.Finally, we discuss conditions for non-Markovian dynamics

Limitações nutricionais de mudas de mangostãozeiro.

Este trabalho teve o objetivo de avaliar, por meio da análise foliar, as limitações nutricionais para produção de mudas de mangostãozeiro. Após 12 meses do plantio, em condições de viveiro, com sombreamento no início do desenvolvimento, foi observado amarelecimento progressivo das folhas novas, com diminuição significativa dos teores foliares de Fe e Mn

Efeito da interação glifosato e zinco na atividade fotossintética da soja.

Os objetivos deste estudo foram avaliar os efeitos da aplicação de glifosato e de doses de Zn sobre a fotossíntese, condutância estomática, concentração de gás carbônico - CO2 e taxa respiratória nas folhas de soja RR no estádio R1 (início do florescimento)

Measuring the Charged Particle Multiplicity with ALICE

The charged particle multiplicity distribution is one of the first measurements that ALICE will be able to perform. The knowledge of this basic property at a new energy is needed to configure Monte Carlo generators correctly with the aim of understanding the background of other, especially rare, processes including new physics. It allows to study the scaling behaviour and to verify model predictions. The unfolding of the measurement is a non-trivial task due to the finite precision and acceptance of the detector. Solutions are based on chi2 minimization or iteratively using Bayes' theorem. Both approaches to unfold the spectrum are presented. Furthermore, the capabilities of the SPD fast OR trigger are shown that enable physics at very high multiplicities.Comment: Proceedings of poster presentation at Quark Matter 2008, 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions in Jaipur, India; to be published in Indian Journal of Physics; 4 pages, 4 figure