Report on "Scheduling in a factory"

In order to carry out their orders of shoe soles, this company has a number of tasks T_1, ..., T_n of different lengths to be assigned to groups of machines. Each group is operated by one worker (two in one case), and an operation cycle corresponds to injection, cooling, and removal of the sole. The time taken at each step varies from one order to another, and when starting a new task a machine needs to be tuned, which takes some extra time. Machines are working in parallel. At the moment the assignment is carried out empirically, and the problem proposed is to optimize the procedure

Invasion Percolation Between two Sites

We investigate the process of invasion percolation between two sites (injection and extraction sites) separated by a distance r in two-dimensional lattices of size L. Our results for the non-trapping invasion percolation model indicate that the statistics of the mass of invaded clusters is significantly dependent on the local occupation probability (pressure) Pe at the extraction site. For Pe=0, we show that the mass distribution of invaded clusters P(M) follows a power-law P(M) ~ M^{-\alpha} for intermediate values of the mass M, with an exponent \alpha=1.39. When the local pressure is set to Pe=Pc, where Pc corresponds to the site percolation threshold of the lattice topology, the distribution P(M) still displays a scaling region, but with an exponent \alpha=1.02. This last behavior is consistent with previous results for the cluster statistics in standard percolation. In spite of these discrepancies, the results of our simulations indicate that the fractal dimension of the invaded cluster does not depends significantly on the local pressure Pe and it is consistent with the fractal dimension values reported for standard invasion percolation. Finally, we perform extensive numerical simulations to determine the effect of the lattice borders on the statistics of the invaded clusters and also to characterize the self-organized critical behavior of the invasion percolation process.Comment: 7 pages, 11 figures, submited for PR

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

Characterization of South American exotic maize (Zea mays L.) populations with opaque phenotype.

Eleven exotic populations of opaque maize from Brazil. Bolívia and Chile, were characterized. Kernels density, lysine and tryptophan contents, total zeins and non-zeins, zein individual fractions, and soluble sugars were analyzed. Although these populations bear soft endosperm, their zein prolifes by gel electrophoresis, the nutritional quality of their proteins as well as the densities of their grains do not follow the patterns present in other opaque maize genotypes. We concluded that these exotic populations are not included in any class of endosperm mutant described so far

Promoter Variation and Expression Levels of Inflammatory Genes IL1A, IL1B, IL6 and TNF in Blood of Spinocerebellar Ataxia Type 3 (SCA3) Patients

Age at onset in spinocerebellar ataxia type 3 (SCA3/MJD) is incompletely explained by the size of the CAG tract at the ATXN3 gene, implying the existence of genetic modifiers. A role of inflammation in SCA3 has been postulated, involving altered cytokines levels; promoter variants leading to alterations in cytokines expression could influence onset. Using blood from 86 SCA3 patients and 106 controls, this work aimed to analyse promoter variation of four cytokines (IL1A, IL1B, IL6 and TNF) and to investigate the association between variants detected and their transcript levels, evaluated by quantitative PCR. Moreover, the effect of APOE isoforms, known to modulate cytokines, was investigated. Correlations between cytokine variants and onset were tested; the cumulative modifier effects of cytokines and APOE were analysed. Patients carrying the IL6*C allele had a significant earlier onset (4 years in average) than patients carrying the G allele, in agreement with lower mRNA levels produced by IL6*C carriers. The presence of APOE*ɛ2 allele seems to anticipate onset in average 10 years in patients carrying the IL6*C allele; a larger number of patients will be needed to confirm this result. These results highlight the pertinence of conducting further research on the role of cytokines as SCA3 modulators, pointing to the presence of shared mechanisms involving IL6 and APOE

Emprego da levedura Pichia membranifaciens CE015 imobilizada em suporte de alginato de cálcio para redução da acetofenona.

Neste trabalho apresentamos o emprego da levedura Pichia membranifaciens CE015 imobilizada em suporte de alginato de cálcio como agente para biorredução. Esta se revelou, a partir de uma triagem, como um potencial agente biocatalítico, uma vez que foram obtidos 76% de conversão da acetofenona ao 1-feniletanol com 98% de ee (S). Em seguida, investigou-se o efeito do emprego das células íntegras imobilizadas em suporte de alginato de cálcio como agentes de biorredução. Em um primeiro ensaio estudou-se a cinética de redução da acetofenona nos tempos de 3 até 96 horas, obtendo-se uma conversão máxima de 87% ao respectivo álcool com 95% de ee. Em seguida, foi estudada a reutilização das esferas em mais 2 ciclos, porém, houve um decréscimo para 67% de conversão mantendo-se constante ee de 95%