A Growth model for DNA evolution

A simple growth model for DNA evolution is introduced which is analytically solvable and reproduces the observed statistical behavior of real sequences.Comment: To be published in Europhysics Letter

A simple deterministic self-organized critical system

We introduce a new continuous cellular automaton that presents self-organized criticality. It is one-dimensional, totally deterministic, without any kind of embedded randomness, not even in the initial conditions. This system is in the same universality class as the Oslo rice pile system, boundary driven interface depinning and the train model for earthquakes. Although the system is chaotic, in the thermodynamic limit chaos occurs only in a microscopic level.Comment: System slightly modified. New results on Liapunov exponents. Submitted for publication (8 pages

Chaos and Synchronized Chaos in an Earthquake Model

We show that chaos is present in the symmetric two-block Burridge-Knopoff model for earthquakes. This is in contrast with previous numerical studies, but in agreement with experimental results. In this system, we have found a rich dynamical behavior with an unusual route to chaos. In the three-block system, we see the appearance of synchronized chaos, showing that this concept can have potential applications in the field of seismology.Comment: To appear in Physical Review Letters (13 pages, 6 figures

Self-Similarity of Friction Laws

The change of the friction law from a mesoscopic level to a macroscopic level is studied in the spring-block models introduced by Burridge-Knopoff. We find that the Coulomb law is always scale invariant. Other proposed scaling laws are only invariant under certain conditions.}Comment: Plain TEX. Figures not include

Exponential Distributions in a Mechanical Model for Earthquakes

We study statistical distributions in a mechanical model for an earthquake fault introduced by Burridge and Knopoff [R. Burridge and L. Knopoff, {\sl Bull. Seismol. Soc. Am.} {\bf 57}, 341 (1967)]. Our investigations on the size (moment), time duration and number of blocks involved in an event show that exponential distributions are found in a given range of the paramenter space. This occurs when the two kinds of springs present in the model have the same, or approximately the same, value for the elastic constants. Exponential distributions have also been seen recently in an experimental system to model earthquake-like dynamics [M. A. Rubio and J. Galeano, {\sl Phys. Rev. E} {\bf 50}, 1000 (1994)].Comment: 11 pages, uuencoded (submitted to Phys. Rev. E

Valores de volume globular e proteína plasmática total em cordeiros no período de amamentação.

Resumo: Este estudo teve como objetivo avaliar a influência do sexo e do tipo racial, sobre os parâmetros de volume globular (VG) e de proteína plasmática total (PPT), bem como a correlação entre o peso, o escore da condição corporal (ECC), VG e PPT em cordeiros das raças Morada Nova e Somali Brasileira, dos 42 dias de nascidos até o desmame aos 120 dias. Foram utilizados 48 cordeiros, distribuídos em quatro grupos de 12 animais, sendo: Machos Somalis Brasileira (MSO), Fêmeas Somalis Brasileira (FSO), Machos Morada Nova (MMN) e Fêmeas Morada Nova (FMN). Os resultados obtidos demonstraram que entre os parâmetros avaliados, apenas o volume globular apresentou diferença significativa (P<0,05) entre os grupos de machos e fêmeas da raça Somalis Brasileira e entre machos da raça Somalis Brasileira e Morada Nova. Conclui-se que o sexo e o grupo racial influenciaram nos valores de volume globular e que houve correlação entre o escore corporal e volume globular nos grupos de animais estudados. Values of globular volume and total plasmatic protein in lambs during the suckling period. Abstract: This study aimed to evaluate the sex and breed type influence on the parameters of globular volume (GV) and total plasmatic protein (TPP), as well as the correlation between the weight, condition of body score (CBS), GV and TPP in sheep of breeds Morada Nova and Brazilian Somali, from 42 days until weaning at 120 days old. A total of 48 lambs were divided into four groups of 12 animals each one, being: Males Brazilian Somalis (MBS), Females Brazilian Somalis (FBS), Males Morada Nova (MMN) and Females Morada Nova (FMN). The results showed that among the factors evaluated, only the globular volume had a significant difference (P<0.05) between males and females groups of Brazilian Somalis breed, and between males of breeds Somali Brazilian and Morada Nova. It is concluded that sex and breed groups influenced the values of globular volume and that was correlation between body condition and globular volume in the studied groups

Análise da vulnerabilidade ambiental.

Revisão sobre o tema vulnerabilidade; Métodos de avaliação da vulnerabilidade ambiental de Bacias Hidrográficas às pressões oriundas de atividades agroindustriais (Vulneragri); Aplicação no método Vuneragri.bitstream/item/33965/1/DO10002.pd