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A taxonomic inventory of oribatid mites from lenga forests in Patagonia Argentina was carried out to assess the taxonomic diversity and to increase the knowledge of their distribution. Nine new records of soil oribatid mites from Argentina are reported. Those species were collected in Chubut province and Tierra del Fuego province. The new registered species belong to the genera Lamellozetes, Hermannia (Phyllhermannia), Crotonia, Kokoppia, Acutoppia, Lanceoppia (Baioppia), Loboppia, Membranoppia(Membranoppia) and Graptoppia (Stenoppia).

The effects of pacing frequency, overdrive duration and stimulus amplitude on the sinus node recovery time (SNRT) were studied in the isolated right atrium of the rat. A positive relationship between pacing frequency and the SNRT was observed, whereas overdrive duration and stimulus amplitude did not affect SNRT. There was no significant interaction among the factors studied. The effect of frequency upon SNRT probably does not involve neurotransmitter release due to stimulation, since in vitro pretreatment with atropine plus propranolol does change the SNRT-frequency relation.