Search

Abstract In animal communication, functionally referential alarm calls elicit the same behavioral responses as their referents, despite their typically distinct bioacoustic traits. Yet the auditory forebrain in at least one songbird species, the black-capped chickadee Poecile atricapillus, responds similarly to threat calls and their referent predatory owl calls, as assessed by immediate early gene responses in the secondary auditory forebrain nuclei. Whether and where in the brain such perceptual and cognitive equivalence is processed remains to be understood in most other avian systems. Here, we studied the functional neurogenomic (non-) equivalence of acoustic threat stimuli perception by the red-winged blackbird Agelaius phoeniceus in response to the actual calls of the obligate brood parasitic brown-headed cowbird Molothrus ater and the referential anti-parasitic alarm calls of the yellow warbler Setophaga petechia, upon which the blackbird is known to eavesdrop. Using RNA-sequencing from neural tissue in the auditory lobule (primary and secondary auditory nuclei combined), in contrast to previous findings, we found significant differences in the gene expression profiles of both an immediate early gene, ZENK (egr-1), and other song-system relevant gene-products in blackbirds responding to cowbird vs. warbler calls. In turn, direct cues of threats (including conspecific intruder calls and nest-predator calls) elicited higher ZENK and other differential gene expression patterns compared to harmless heterospecific calls. These patterns are consistent with a perceptual non-equivalence in the auditory forebrain of adult male red-winged blackbirds in response to referential calls and the calls of their referents.

The /EC decay of Tl to excited states in the daughter nuclei Hg has been investigated at the CERN on-line isotope mass separator facility. In both Tl nuclei two β-decaying states were observed. In the case of 184Tl, narrow-band laser spectroscopy could be used to disentangle the decay of both isomers. In 182Hg a precise energy of 335 (1) keV for the state was measured together with its feeding from a tentatively proposed state at 973 keV. Large conversion coefficients for the transition in Hg were measured to be 7.2 (13) and 14.2 (36), respectively, evidencing a strong E0 component. [ABSTRACT FROM AUTHOR]

α-decay spectroscopy of Tl has been performed at the CERN isotope separator on-line (ISOLDE) facility. New fine-structure α decays have been observed for both isotopes. α-decay branching ratios of 0.089(19)%, 0.047(6)% and 1.22(30)% have been deduced for the (10−), (7+) and (2−) states respectively in 184Tl and a lower limit of 0.49% for the α-decay branching ratio of 182Tl. A new half-life of 9.5(2) s for the (2−) state in 184Tl and 1.9(1) s for the low-spin state in 182Tl has been deduced. Using α–γ coincidence analysis, multiple γ rays were observed de-exciting levels in Au fed by Tl α decays. The γ transitions connecting these low-lying states in Au are essential to sort the data and possibly identify bands from in-beam studies in these isotopes. Owing to the complex fine-structure α decays and limited knowledge about the structure of the daughter nuclei, only partial level schemes could be constructed for both gold isotopes in the present work. Reduced α-decay widths have been calculated and are compared with values obtained in neighboring odd-A and even-A thallium isotopes. Except for the allowed α decay of the 184Tl (10−) state, the other fine-structure α decays observed in this study are hindered. This points to strong structural changes between parent thallium and daughter gold isotopes. [ABSTRACT FROM AUTHOR]