Royal Society Open Science最新文献

The 'modern' kangaroos and wallabies (subfamily Macropodinae) are herbivorous marsupials characterized by their bipedal hopping gait. Macropodines radiated through the Late Miocene and Pliocene (11.6-2.6 Ma) as Australia aridified. Dorcopsoides fossilis, known only from the Late Miocene Alcoota locality in central Australia, is the earliest undisputed macropodine. Although first described in 1967 from craniodental and postcranial fragments, it has since received minimal attention, despite the accumulation of many more specimens and the potential they hold for shedding light on kangaroo evolution. Here we describe its limb morphology and make comparisons with limb bones of extant species with various locomotory modes and habitat preferences. Though D. fossilis is generally similar to living low-geared hoppers, it has certain features seen in higher-geared macropodines that imply some ability to hop powerfully and efficiently. These features indicate the species was adapted to moving through open habitats, consistent with past interpretations of the Alcoota palaeoenvironment. As in modern macropodines, the pronounced size bimodality in forelimb elements of D. fossilis likely represents sexual dimorphism. Our results strongly reinforce the macropodine affinity of D. fossilis, demonstrating that the dominant features of the macropodine skeletal plan were in place well before the end of the Miocene.

Hawaiian monk seals (HMS; Neomonachus schauinslandi) are endemic and endangered with a population of approximately 1600 individuals. While research has provided extensive information on HMS biology, movements and population ecology, its underwater vocal behaviour remains largely undocumented, with previous descriptions limited to two individuals in human care. To broaden our understanding of sound production in free-ranging seals, we deployed passive acoustic recorders at five sites across the Hawaiian archipelago. From >4500 h of recordings, we manually detected and classified >23 000 underwater vocalizations. A discriminant function analysis of 10 call types yielded an average correct classification rate of 63%. We identified 25 call types, including five published elemental calls and 20 novel calls. Nineteen of the novel call types were combinational calls-an undocumented communication strategy in pinnipeds. The novel Whine, captured via biologging tag- and citizen-scientist videos, provided a rare example of context-specific call use in pinnipeds. Vocalizations were low frequency (<1 kHz), short-medium duration (<7 s), with 66% occurring in bouts. Calls were detected throughout the day at three of five sites, with peaks at night and late afternoon. These findings establish a baseline for HMS vocal behaviour and emphasize the importance of acoustic communication in future research and conservation efforts.

This study proposes a systems approach to explore the entropy signatures of war phases on social cohesion dynamics in Ukraine (2004-2025). Using a psycholinguistic time series of online searches for first-person plural pronouns, we quantified social cohesion complexity using sample entropy and refined composite multiscale entropy (RCMSE). Analyses reveal distinct signatures between war phases over time for both metrics, with, respectively, R ² = 0.57 and R ² = 0.95. Relative to peace and full invasion, social cohesion entropy decreased under partial invasion and displayed more anti-persistent behaviour. While social cohesion was most dysfunctional under partial invasion, entropy signatures of full-scale invasion and peace were relatively close. These results offer insights into the impact of interstate aggression on social cohesion and contribute to a dynamical systems understanding of warfare as a systemic shock. The methodology provides a framework for monitoring and predicting societal resilience in response to significant events.

This study presents a detailed first-principles investigation of the effects of CO and NO gas adsorption on the structural, electronic and optical properties of armchair silicon-tin nanoribbons (ASiSnNRs). Cohesive and adsorption energy calculations indicated that the ASiSnNR structure was thermodynamically stable, with physisorption for CO (-0.01 eV) and chemisorption for NO (-0.68 eV). Electronic band structure analysis revealed that pristine ASiSnNRs exhibited semiconducting behaviour with a narrow band gap (approx. 0.43 eV), which slightly widened upon CO adsorption and transitioned to a metallic state upon NO adsorption because of the strong orbital hybridization and charge transfer effects. Charge density and wave function analyses confirmed this mechanism, with particular emphasis on the role of the π* orbital of the CO molecule. The dielectric function, optical absorption, reflection spectra and joint density of states show significant enhancements in anisotropic optical properties after CO adsorption, especially in the ultraviolet region. These findings suggest the strong potential of ASiSnNRs for selective and highly sensitive gas-sensing applications, particularly for the detection of NO.

Extrusion-based additive manufacturing (AM) is a popular technique used in the fabrication of three-dimensional constructs. Owing to the nonlinear manner in which process parameters affect resolution and printability, the optimal combination remains platform and material specific. This study proposes a user-friendly, adaptable model to predict the diameter of a printed line of material through extrusion-based bioprinting. Exploiting the geometry of an arbitrary, axisymmetric nozzle and assuming a power-law fluid, the model generated determines a relationship between the printed filament diameter and the pressure drop, nozzle travel speed, nozzle geometry and material flow properties. Employing the model prior to printing enables engineers to restrict process parameter space and minimize the dependence on the current print-and-test methodology before an optimal combination of process parameters is determined. Two materials (a poly(vinyl alcohol)-based (PVA-based) hydrogel and Nivea Crème), two temperature conditions and three nozzle sizes were used for model validation, presenting good agreement with model predictions. When the shear-thinning property is included, the coefficient of determination, R ², is greater than 0.97. This model provides context and direction for future optimization-driven design research for this advancing manufacturing technology.

We present evidence that the faint polarized moonlight pattern of the sky can be used for navigation in a diurnal animal, the bull ant Myrmecia tarsata. This comes despite this species lacking the highly refined low-light visual specializations of nocturnal bull ants. Celestial bodies can provide animals with directional information, yet direct observation can often be occluded. Positional information of solar and lunar cues can be estimated via their polarized light pattern, present across the sky. The sun's polarization pattern is widely used in animals, and a similar, yet much fainter, pattern is produced by the moon. However, given the inherent variability of the moon, it is unknown how widespread moonlight use is in navigating animals. Here, M. tarsata, which forages throughout the day, returning home at sunset, uses both solar and lunar polarized light to navigate. We compare this to the closely related nocturnal sympatric Myrmecia midas navigating under identical conditions. Both species clearly use solar and lunar polarized light patterns to navigate, but M. tarsata showed degraded performance under polarized moonlight as a function of lunar phase, decreasing performance as illumination decreased. Myrmecia midas, in contrast, exhibited impressive attendance to lunar polarization patterns throughout the lunar month.

The human propensity for prosocial behaviour has no equal, not even in our closest living relatives, the chimpanzees. However, it remains unclear whether this difference is grounded in the sheer perception and cognitive evaluation of prosociality. We investigated how two hominid species, chimpanzees and humans, perceive third-party social interactions with prosocial, neutral and antisocial agents. Using a touchscreen paradigm, human and chimpanzee participants freely selected between two actors after viewing their interactions, ranging from pro- to antisocial. Contrary to current thinking, we found no evidence for species differences in their choices for agents, regardless of whether interactions were between conspecifics or not. Both humans and chimpanzees demonstrated comparable sensitivity to prosociality, challenging existing views of a profound chimpanzee-human difference in prosociality. Instead, our results indicate that the perception of social interactions is similar across hominids, but that humans have evolutionarily diverged in how they act upon such perceptions.

Group-living provides many fitness benefits for individual members, including improved foraging and predator vigilance. If such benefits are especially pronounced for sick members, group-living can act as a form of behavioural tolerance by offsetting mortality costs of infection. We experimentally tested this possibility by examining whether group-living impacts foraging and anti-predator behaviours in house finches (Haemorhous mexicanus) with or without conjunctivitis caused by Mycoplasma gallisepticum. We varied both group-living (single-housed or group-housed) and infection (M. gallisepticum-inoculated or sham-inoculated) and performed four behavioural assays at peak infection: two assessing how birds respond to foraging opportunities and two assessing responses to predation threats. Both social treatment and disease status influenced most measured behaviours, with single-housed, diseased birds consistently the least responsive to foraging opportunities and predation threats. While group-living also benefited healthy individuals (e.g. led to faster responsiveness) in most behavioural assays, our results suggest that diseased birds particularly benefit from group-living. Further, detected behavioural differences with group-living were not explained by effects of sociality on disease severity or pathogen load, which did not differ with group-living. By augmenting behaviours key to survival during infection, group-living may act as a form of behavioural tolerance for social species, with important implications for transmission dynamics.

A sensitive method for sulfur dioxide (SO₂) determination was developed with reaction cell inductively coupled plasma mass spectrometer (ICP-MS) by preconcentrating SO₂ from gas samples to solutions. O₂ flow rate was set at 0.7 ml min^-1 for optimal signal to noise ratio at m/z 48 (³²S¹⁶O⁺). Favourable conditions to prepare SO₂ concentrated solutions including sampling flow rate, the volume of concentrated solution, the number of perfluoroalkoxy alkane (PFA) bubble absorption bottles and the composition of concentrated solution were investigated using SO₂ in nitrogen gas reference materials within the range of 5.00 parts per billion (ppb) to 1.00 parts per million (ppm). A limit of detection (LOD) of 0.11 ppb was achieved, corresponding to 100 l 5.00 ppb SO₂ with a sampling flow rate of 0.5 l min^-1. This method also showed favourable selectivity in the assay of atmosphere SO₂ level, providing its promising further application in monitoring gaseous environmental pollutants.