The Penna model for biological ageing on a lattice: spatial consequences of child-care

We introduce a square lattice into the Penna bit-string model for biological ageing and study the evolution of the spatial distribution of the population considering different strategies of child-care. Two of the strategies are related to the movements of a whole family on the lattice: in one case the mother cannot move if she has any child younger than a given age, and in the other case if she moves, she brings these young children with her. A stronger condition has also been added to the second case, considering that young children die with a higher probability if their mothers die, this probability decreasing with age. We show that a highly non uniform occupation can be obtained when child-care is considered, even for an uniform initial occupation per site. We also compare the standard survival rate of the model with that obtained when the spacial lattice is considered (without any kind of child-care).Comment: 8 pages, 6 Postscript figure

Applications and Sexual Version of a Simple Model for Biological Ageing

We use a simple model for biological ageing to study the mortality of the population, obtaining a good agreement with the Gompertz law. We also simulate the same model on a square lattice, considering different strategies of parental care. The results are in agreement with those obtained earlier with the more complicated Penna model for biological ageing. Finally, we present the sexual version of this simple model.Comment: For Int.J.Mod.Phys.C Dec. 2001; 11 pages including 6 fig

Some properties of two Nambu--Jona-Lasinio -type models with inputs from lattice QCD

We investigate the phase diagram of the so-called Polyakov--Nambu--Jona-Lasinio (PNJL) model at finite temperature and nonzero chemical potential. The calculations are performed in the light and strange quark sectors ($u$, $d$, $s$), which includes the 't Hooft instanton induced interaction term that breaks the axial symmetry, and the quarks are coupled to the (spatially constant) temporal background gauge field. On one hand, a special attention is payed to the critical end point (CEP). The strength of the flavor-mixing interaction alters the CEP location, since when it becomes weaker the CEP moves to low temperatures and can even disappear. On the other hand, we also explore the connection between QCD, a nonlocal Nambu--Jona-Lasinio type model and the Landau gauge gluon propagator. Possible links between the quenched gluon propagator and low energy hadronic phenomenology are investigated.Comment: Contribution to the International Meeting "Excited QCD", Peniche, Portugal, 06 - 12 May 201

Simulations of a mortality plateau in the sexual Penna model for biological ageing

The Penna model is a strategy to simulate the genetic dynamics of age-structured populations, in which the individuals genomes are represented by bit-strings. It provides a simple metaphor for the evolutionary process in terms of the mutation accumulation theory. In its original version, an individual dies due to inherited diseases when its current number of accumulated mutations, n, reaches a threshold value, T. Since the number of accumulated diseases increases with age, the probability to die is zero for very young ages (n = T). Here, instead of using a step function to determine the genetic death age, we test several other functions that may or may not slightly increase the death probability at young ages (n < T), but that decreases this probability at old ones. Our purpose is to study the oldest old effect, that is, a plateau in the mortality curves at advanced ages. Imposing certain conditions, it has been possible to obtain a clear plateau using the Penna model. However, a more realistic one appears when a modified version, that keeps the population size fixed without fluctuations, is used. We also find a relation between the birth rate, the age-structure of the population and the death probability.Comment: submitted to Phys. Rev.

Montemuro - A Última Rota da Transumância

A profilaxia sanitária de algumas doenças infecto-contagiosas que afectam os ovinos recomenda a restrição da circulação de rebanhos, impondo também sérias restrições às transições de animais. Duas das doenças de maior importância sanitária em ovinos, quer pela sua elevada contagiosidade, quer pelas suas consequências na saúde animal são a Brucelose e a Agaláxia contagiosa. Destaca-se a Brucelose por ser a considerada a maior Zoonose do mundo e pela incidência elevada na população humana portuguesa e em especial na região centro. Ambas as doenças se traduzem por perdas económicas relevantes nos efectivos que atingem e ambas exigem um controlo preferencialmente do tipo profiláctico uma vez que a sua terapia se revela difícil e mal sucedida na maioria dos casos. Este controlo profiláctico acarreta medidas exigentes e dispendiosas que passam pelo despiste serológico e abate dos animais positivos no caso da Brucelose e vacinações semestrais no caso da Agaláxia, bem como medidas complementares de higiene que visam impedir o contágio entre animais da mesma exploração, entre animais de explorações distintas e cujo incumprimento impede qualquer eficácia das medidas anteriores. Para que a transumância se torne uma prática segura é essencial que, à realidade destes riscos sanitários, seja dada a importância devida por todos os intervenientes na sanidade animal e sejam implementadas medidas seguras para o seu controlo. Até lá, não poderemos deixar de os considerar uma verdadeira ameaça à prática da transumância no nosso país e em particular na nossa região

EFFECTS OF EARLY PROTEIN MALNUTRITION AND REPEATED TESTING UPON LOCOMOTOR AND EXPLORATORY BEHAVIORS IN THE ELEVATED PLUS-MAZE

An elevated plus-maze was used to investigate the effects of repeated testing on the locomotor and exploratory behaviors of malnourished rats. Pup malnutrition was induced during the lactation period (0 to 21 days of age) by feeding the dams a protein-deficient diet (6% protein) and the animals were allowed to recover from weaning to 70 days of age by eating a commercial lab chow diet. Control animals were suckled by dams receiving normal protein diet (16% protein) during the lactation period and were fed a commercial lab chow diet after weaning. At 70 days, malnourished and control animals were placed on the central platform of the elevated plus-maze facing an enclosed arm and allowed to explore for 5 min. This procedure was repeated at 24-h intervals of 6 days. The repeated testing in the elevated plus-maze did not change the total number of arm entries and attempts to enter open arms, but decreased the percentage of open arm entries, time spent in open arms, and total time spent on the central platform. These data suggest an increase in anxiety with repeated testing in the elevated plus-maze. In addition, the malnourished animals showed a large number of these animals as compared to control. The elevated plus-maze proved to be useful animal model to evaluate exploratory behaviors in early protein malnourished animals. Keywords: Early protein malnutrition Elevated plus-maze Impulsiveness Exploration Anxiety Repeated testing

Concentração e qualidade de DNA's de açaizeiro tipo branco (Euterpe oleracea mart.) obtidos da Embrapa Amazônia Oriental.

O açaizeiro (Euterpe oleracea Mart.) é uma palmeira perene, tropical e frutífera cujo habitat natural se encontra nas várzeas da Amazônia, onde o Pará vincula como principal produtor e consumidor. Destaca-se mundialmente pela polpa congelada e diversos subprodutos. Essa palmeira é constituída por algumas variedades que diferem especialmente, pelo tamanho e coloração dos frutos, dentre elas tem-se o açaí branco que vem sendo objeto de vários estudos nas instituições da Amazônia. Objetivou-se determinar a concentração e a qualidade de DNA?s de açaizeiros tipo branco obtidos na Embrapa Amazônia Oriental. Foram coletados folíolos de folhas de 222 plantas de açaí tipo branco conservado no Banco Ativo de Germoplasma da Embrapa Amazônia Oriental. A extração de DNA foi feita pelo método de CTAB (Brometo de Cetil Trimetilamônio) utilizando o protocolo de Doyle e Doyle com modificações. Os DNA?s foram quantificados em gel de agarose a 0,8% com o auxílio de três concentrações de DNA lambda (50, 100 e 200 ng/ul) como padrão e as imagens obtidas foram capturadas e lidas no software Labimage. As concentrações foram analisadas por estatísticas descritivas. As 222 amostras de DNA apresentaram 100% de aproveitamento, mas os pellets obtidos apresentaram tamanhos distintos e foram diluídos em volumes distintos, variando entre 50 a 250µl. As quantidades dos DNA?s obtidos variaram de 101,37 a 620,27 ng.&#956;l -1 apresentando média de 269,39 ng.&#956;l -1. As bandas obtidas apresentaram arrastes e presença de RNA, sendo submetidas a tratamentos para melhoria das qualidades. Portanto, pode-se considerar que os DNA?s de açaizeiro tipo branco obtidos possuem excelentes concentrações e qualidades.VII ENAAg