Biomedical subjects
Publications and source records attributed to C Auerbach.
Translocations between the two large autosomes were scored in the progeny of males that had been fed mitomycin-C. The frequencies were the same in spermatogonia sampled after 12 and 25 days and in spermatozoa stored for the same periods in untreated females.
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The Lifschytz-Lindley model of spermatogenesis in heterogametic animals postulates a stage of gene inactivation during spermatogenesis, which affects the X-chromosome and the autosomes at different times. The frequent male infertility of X-ray induced X-autosome translocations is attributed to disruption in the timing of this stage by breaks that occur in the interior euchromatic portion of the X. Indeed, all male-fertile X-ray induced translocations between the X and an autosome had their breakpoints in the proximal or distal portion of the X. We now show that this was true also for 16 male-fertile X-autosome translocations that had been induced by an alkylating agent, diepoxybutane (DEB). The significantly higher proportion of male-fertile X-translocations in this experiment than in experiments with ionizing radiation apparently is due to a preference of diepoxybutane for the induction of breaks in the "permissive" regions of the X. Older data suggest that this preference is even stronger for mustard gas as chromosome-breaking agent. While these data do not add further evidence to the Lifschytz-Lindley model, they remove a potential objection to it.
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This experiment compared two modes of practice at a difficult frequency discrimination, i.e., one in which the frequency difference was initially correctly discriminated only 65% of the trials in a two-alternative forced-choice task. One group of Ss (N = 13) was assigned to a progressive-practice group, in which the frequency difference to be discriminated was progressivley changed from a large, easy, difference to the difficult, small, difference. The other group of Ss (N = 13) received the same amount of practice as the first, but all at the difficult discrimination. Only the progressive-practice group improved their discrimination performance. Since no feedback was given, the effect of progressive practice is interpreted as "shaping" Ss' attentional response by virtue of the information provided by the successively more difficult discriminations. This "shaping" process is potentially available as a learning mechanism for other fine discriminations.
Eye contact is a non-verbal behavior category of major concern in the study of social interaction. Within this category many behaviors are included which serve a wide range of functions. It was hypothesied that (1) one of the important stimulus properties that distinguish these behaviors is the movement pattern of the eye and (2) that people use different criteria to judge whether another person is looking at them, depending upon whether the other person is displaying a dynamic or static eye presentation. Data are presented to support these hypotheses.
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