First acoustic evidence of signature whistle production by spinner dolphins (Stenella longirostris).

A dolphin's signature whistle (SW) is a distinctive acoustic signal, issued in a bout pattern of unique frequency modulation contours; it allows individuals belonging to a given group to recognize each other and, consequently, to maintain contact and cohesion. The current study is the first scientific evidence that spinner dolphins (Stenella longirostris) produce SWs. Acoustic data were recorded at a shallow rest bay called "Biboca", in Fernando de Noronha Archipelago, Brazil. In total, 1902 whistles were analyzed; 40% (753/1,902) of them were classified as stereotyped whistles (STW). Based on the SIGID method, 63% (472/753) of all STWs were identified as SWs; subsequently, they were categorized into one of 18 SW types. SWs accounted for 25% (472/1,902) of the acoustic repertoire. External observers have shown near perfect agreement to classify whistles into the adopted SW categorization. Most acoustic and temporal variables measured for SWs showed mean values similar to those recorded in other studies with spinner dolphins, whose authors did not differentiate SWs from non-SWs. Principal component analysis has explained 78% of total SW variance, and it emphasized the relevance of shape/contour and frequency variables to SW variance. This scientific discovery helps improving bioacoustics knowledge about the investigated species. Future studies to be conducted in Fernando de Noronha Archipelago should focus on continuous investigations about SW development and use by S. longirostris, expanding individuals' identifications (Photo ID and SW Noronha Catalog), assessing long-term whistle stability and emission rates, and making mother-offspring comparisons with sex-based differences.

Acoustic recording of false killer whale (Pseudorca crassidens) from Mexico (L).

This study collected acoustic information on false killer whales (Pseudorca crassidens) in Mexican waters, close to Roca Partida Island, Revillagigedo Archipelago. In total, 321 whistles were collected after we found a group with at least ten individuals. The high prevalence of ascending contour types [upsweep (type I): 42.99%] contradicted the idea that false killer whales mostly produce constant whistles. Lack of well-established reproducibility criteria for whistle type categorization among studies may have generated results different from those expected for signal modulation. Future acoustic and ecological studies should be conducted to help clarify these findings and expand the limited knowledge about this species.

Radiotherapy and immediate expander/implant breast reconstruction: should reconstruction be delayed?

Chest wall irradiation is very common for mastectomy patients that have opted for immediate breast reconstruction. We reviewed a 6 year experience with tissue expander implant reconstruction with and without radiotherapy in 97 patients. All patients were evaluated with respect to aesthetic outcome, infection, implant exposure, capsular contracture, displacement and failure of the reconstruction; more than 50% of our irradiated patients resulted in a complication. The findings of this study demonstrate that the rate of complications and the rate of patients requiring corrective surgeries in irradiated patients is significant in early follow up.