Development of bed-building behaviors in captive chimpanzees (Pan troglodytes): Implication for critical period hypothesis and captive management

Wild great apes build beds for sleeping by combining tree branches or other vegetation, but the development of this behavior is poorly understood. We investigated the development of bed-building behaviors by conducting complementary cross-sectional and longitudinal studies of captive chimpanzees. In the cross-sectional study, we created an ethogram of behaviors related to bed-building by observing 59 chimpanzees living at the Kumamoto Sanctuary, Kyoto University, and the Kyoto City Zoo. In the longitudinal study, we installed bed-building platforms, provided branches on the platforms on a regular basis, and recorded behaviors of five chimpanzees (including an infant born in 2013) over a 3-year period from February 2015 to February 2018 at the Kyoto City Zoo (total 490.7 h). We found that all the chimpanzees performed some form of bed-building behavior but wild-born chimpanzees possessed more sophisticated techniques than captive-born chimpanzees. We also found that although the offspring of a wild-born female only showed simple techniques at the beginning of the longitudinal study, his repertoire of bed-building behaviors became as complex as that of his mother by the age of five. Our results suggest that improved bed-building behaviors can be supported in captive-born great apes by providing learning opportunities during appropriate stages of development

Selective Synthesis and Luminescence Properties of Nanocrystalline GdF3:Eu 3+

GdF3:Eu3+ nanophosphors with hexagonal or orthorhombic structure have been succeeded to be selectively synthesized at room temperature for the first time via a simple soft chemical route. The structure and morphology of GdF3:Eu3+ nanophosphors were controlled by using different fluoride precursors. Hexagonal GdF3:Eu3+ nanocrystals were formed when NaBF4 was used as a fluoride precursor, while orthorhombic GdF3:Eu3+ nanocrystals were obtained with NaF or NH4F fluoride precursor. It was also experimentally revealed that hexagonal GdF3:Eu3+ nanophosphors emitted essentially stronger Eu3+ luminescence than orthorhombic ones did. The formation mechanism of GdF3 nanocrystals and the possible reasons of the strong PL in hexagonal were discussed

Spiral Structure in WZ Sagittae around the 2001 Outburst Maximum

Intermediate resolution phase-resolved spectra of WZ Sge were obtained on five consecutive nights (July 23 -- 27) covering the initial stage of the 2001 superoutburst. Double-peaked emission lines of He\textsc{II} at 4686 \AA, which were absent on July 23, emerged on July 24 together with emission lines of C\textsc{III} / N\textsc{III} Bowen blend. Analyses of the He\textsc{II} emission lines using the Doppler tomography revealed an asymmetric spiral structure on the accretion disk. This finding demonstrates that spiral shocks with a very short orbital period can arise during the initial stage of an outburst and may be present in all SU UMa stars.Comment: 5 pages, 8 figures, accepted for publication in PAS

Spectra of V1405 Cas at the very beginning indicate a low-mass ONeMg white dwarf progenitor

The lowest possible mass of ONeMg white dwarfs (WDs) has not been clarified despite its importance in the formation and evolution of WDs. We tackle this issue by studying the properties of V1405 Cas (Nova Cassiopeiae 2021), which is an outlier given a combination of its very slow light-curve evolution and the recently reported neon-nova identification. We report its rapid spectral evolution in the initial phase, covering 9.88, 23.77, 33.94, 53.53, 71.79, and 81.90 hours after the discovery. The first spectrum is characterized by lines from highly-ionized species, most noticeably He II and N III. These lines are quickly replaced by lower-ionization lines, e.g., N II, Si II, and O I. In addition, Al II (6237 \r{A}) starts emerging as an emission line at the second epoch. We perform emission-line strength diagnostics, showing that the density and temperature quickly decrease toward later epochs. This behavior, together with the decreasing velocity seen in H$\alpha$, H$\beta$, and He I, indicates that the initial nova dynamics is reasonably well described by an expanding fireball on top of an expanding photosphere. Interestingly, the strengths of the N III and Al II indicate large abundance enhancement, pointing to an ONeMg WD progenitor as is consistent with its neon-nova classification. Given its low-mass nature inferred by the slow light-curve evolution and relatively narrow emission lines, it provides a challenge to the stellar evolution theory that predicts the lower limit of the ONeMg WD mass being $\sim$ 1.1 $M_\odot$.Comment: 15 pages, 5 figures, 2 tables, accepted to Ap

Synthesis and Self-Assembly of Gold Nanoparticles by Chemically Modified Polyol Methods under Experimental Control

In our present research, bottom-up self-assembly of gold (Au) nanoparticles on a flat copper (Cu) substrate is performed by a facile method. The very interesting evidence of self-assembly of Au nanoparticles on the top of the thin assembled layer was observed by scanning electron microscopy (SEM). We had discovered one of the most general and simple methods for the self-assembly of metal nanoparticles. The general physical and chemical mechanisms of the evaporation process of the solvents can be used for self-assembly of the as-prepared nanoparticles. The important roles of molecules of the used solvents are very critical to self-assembly of the as-prepared Au nanoparticles in the case without using any polymers for those processes. It is clear that self-assembly of such one nanosystem of the uniform Au nanoparticles is fully examined. Finally, an exciting surface plasmon resonance (SPR) phenomenon of the pure Au nanoparticles in the solvent was fully discovered in their exciting changes of the narrow and large SPR bands according to synthesis time. The SPR was considered as the collective oscillation of valence electrons of the surfaces of the pure Au nanoparticles in the solvent by incident ultraviolet-visible light. Then, the frequency of light photons matches the frequency of the oscillation of surface electrons of the Au nanoparticles that are excited