3 resultados para Aerocar Company of Detroit

em Instituto Superior de Psicologia Aplicada - Lisboa


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Vocal differentiation is widely documented in birds and mammals but has been poorly investigated in other vertebrates, including fish, which represent the oldest extant vertebrate group. Neural circuitry controlling vocal behaviour is thought to have evolved from conserved brain areas that originated in fish, making this taxon key to understanding the evolution and development of the vertebrate vocal-auditory systems. This study examines ontogenetic changes in the vocal repertoire and whether vocal differentiation parallels auditory development in the Lusitanian toadfish Halobatrachus didactylus (Batrachoididae). This species exhibits a complex acoustic repertoire and is vocally active during early development. Vocalisations were recorded during social interactions for four size groups (fry: <2 cm; small juveniles: 2-4 cm; large juveniles: 5-7 cm; adults >25 cm, standard length). Auditory sensitivity of juveniles and adults was determined based on evoked potentials recorded from the inner ear saccule in response to pure tones of 75-945 Hz. We show an ontogenetic increment in the vocal repertoire from simple broadband-pulsed 'grunts' that later differentiate into four distinct vocalisations, including low-frequency amplitude-modulated 'boatwhistles'. Whereas fry emitted mostly single grunts, large juveniles exhibited vocalisations similar to the adult vocal repertoire. Saccular sensitivity revealed a three-fold enhancement at most frequencies tested from small to large juveniles; however, large juveniles were similar in sensitivity to adults. We provide the first clear evidence of ontogenetic vocal differentiation in fish, as previously described for higher vertebrates. Our results suggest a parallel development between the vocal motor pathway and the peripheral auditory system for acoustic social communication in fish.

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The function of fish sounds in territorial defence, in particular its influence on the intruder's behaviour during territorial invasions, is poorly known. Breeding Lusitanian toadfish males (Halobatrachus didactylus) use sounds (boatwhistles) to defend nests from intruders. Results from a previous study suggest that boatwhistles function as a 'keep-out signal' during territorial defence. To test this hypothesis we performed territorial intrusion experiments with muted Lusitanian toadfish. Males were muted by making a cut and deflating the swimbladder (the sound-producing apparatus) under anaesthesia. Toadfish nest-holder males reacted to intruders mainly by emitting sounds (sham-operated and control groups) and less frequently with escalated bouts of fighting. When the nest-holder produced a boatwhistle, the intruder fled more frequently than expected by chance alone. Muted males experienced a higher number of intrusions than the other groups, probably because of their inability to vocalise. Together, our results show that fish acoustic signals are effective deterrents in nest/territorial intrusions, similar to bird song.

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O crescente interesse na compreensão e na gestão da interface trabalho-família provém das já demonstradas consequências do conflito trabalho-família no bem estar profissional e pessoal e no desempenho dos papéis de trabalho e de família. A participação das mulheres na força de trabalho levou a que combinem as responsabilidades familiares e profissionais. A combinação do papel de trabalho e do papel de família poderá levar ao conflito trabalho-família. A investigação realizada centra-se na forma como os indivíduos manipulam as exigências do trabalho e da família na tentativa de criar modelos de relacionamento e de actividades que sejam gerí- veis. Actualmente, as preocupações dos investigadores vão mais longe e procuram, também, encontrar soluções no local de trabalho que facilitem a conciliação entre o trabalho e a família. O objectivo deste estudo é o de verificar a existência e as diferenças na percepção do conflito trabalho- família entre homens e mulheres. Os dados foram obtidos através de entrevistas a 33 trabalhadores de uma empresa de produtos lácteos.