On the almost sure central limit theorem for ARX processes in adaptive tracking

The goal of this paper is to highlight the almost sure central limit theorem for martingales to the control community and to show the usefulness of this result for the system identification of controllable ARX(p,q) process in adaptive tracking. We also provide strongly consistent estimators of the even moments of the driven noise of a controllable ARX(p,q) process as well as quadratic strong laws for the average costs and estimation errors sequences. Our theoretical results are illustrated by numerical experiments

DNA hypermethylation in sodium butyrate-treated WI-38 fibroblasts

Sodium butyrate is very often used to alter gene expression in cultured cells. In this study, we examined the effects of this compound on various cellular events in WI-38 human embryonic lung fibroblasts in culture. During a 16-20-h treatment at sodium butyrate concentrations of between 5 and 20 mM, no adverse effects on cell morphology were observed. However, cell division and DNA synthesis were reversibly inhibited, the latter by 85, 80, and 70% at sodium butyrate concentrations of 5, 10, and 20 mM, respectively. Although overall protein synthetic activity was not significantly affected, RNA synthesis decreased to 76% of the control values at a sodium butyrate concentration of 5 mM. Butyrate treatment also caused hypermethylation of DNA cytosines as determined by differential digestion by MspI/HpaII restriction endonucleases and by high performance liquid chromatography analysis of the DNA. The 5-methylcytosine content of the DNA in untreated WI-38 fibroblasts was 2.94 +/- 0.46% of total cytosine residues, while in cultures treated with 5, 10, and 20 mM sodium butyrate, these values were 5.76 +/- 0.28, 5.91 +/- 0.37, and 6.8 +/- 0.44%, respectively. An interesting feature is that this hypermethylation occurred in DNA which was synthesized in the presence of sodium butyrate (newly synthesized) as well as in DNA which had been synthesized before butyrate administration (pre-existing DNA). The hypermethylated state was conserved only in the former situation, since the methylcytosines were rapidly lost in the subsequent generation in the latter case. It would therefore appear that methylcytosines are maintained after cell replication only if they are generated on newly synthesized DNA