Yoichi Sakai

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With the goal of developing a conversational humanoid that can serve as a companion for people with dementia, we propose an autonomous virtual agent that can generate backchannel feedback, such as head nods and verbal acknowledgement, on the basis of acoustic information in the user's speech. The system is also capable of speech recognition and language(More)
Protogynous hermaphroditism, female-to-male sex change, is well known among reef fishes where large males monopolize harems of females. When the dominant male disappears from a harem, the largest female may change sex within a few weeks. Recently, from experiments with some protogynous haremic fishes in which two males' cohabitated, it was confirmed that(More)
With the increasing average life expectancy of world population, there are more and more dementia patients, and the needs of assistive technology emerges. According to the literature, the progress of cognitive impairment can be suppressed to be slower if the patients is constantly in calm mood. An effective way is suggested by keeping them in social(More)
The genes folliculogenesis specific basic helix-loop-helix (facor in the germline alpha, Figla) and doublesex and mab-3 related transcription factor 1 (Dmrt1) are female- and male-specific genes that play key roles in sex differentiation. To obtain a better understanding of the molecular mechanisms underlying female-to-male sex change, we cloned the cDNAs(More)
We tested the hypothesis that the highly flexible feeding repertoire of juvenile Chaetodipterus faber reflects their trophic adaptability by quantifying the feeding behaviour of juveniles in situ, for the first time, in a northeastern Brazilian estuary. The fishes presented a preference for alga-rich habitats, irrespective of the substrate type chosen(More)
We designed a new inverse PCR protocol combined with switching mechanism at 5' end of RNA transcript (SMART) technology, and applied it to the cloning of teleost corticotropin-releasing hormone precursor cDNA. Due to the advantages of both techniques, this method can efficiently amplify the complete 5'- and 3'-ends of cDNA in a single reaction, and might(More)
Mimesis is a relatively widespread phenomenon among reef fish, but the ontogenetic processes relevant for mimetic associations in fish are still poorly understood. In the present study, the allometric growth of two allopatric leaf-mimetic species of ephippid fishes, Chaetodipterus faber from the Atlantic and Platax orbicularis from the Indo-Pacific, was(More)
Primary males that function as males throughout their lives are often found among protogynous fishes such as wrasses and parrotfishes. However, the issue of whether the sexuality of primary males involves gonochorism or hermaphroditism remains uncertain. To clarify this, we implanted estradiol-17beta (E2) into the body cavities of primary males of two(More)