Browse Articles

RNAi of the elastomeric protein resilin reduces jump velocity and resilience to damage in locusts

Resilin, an elastomeric protein with remarkable physical properties that outperforms synthetic rubbers, is a near-ubiquitous feature of the power amplification mechanisms used by jumping insects. Catapult-like mechanisms, which incorporate elastic energy stores formed from a composite of stiff cuticle and resilin, are frequently used by insects to translate slow muscle contractions into rapid-release recoil movements. The precise role of resilin in these jumping mechanisms remains unclear, however. We used RNAi to reduce resilin deposition in the principal energy-storing springs of the desert locust ( Schistocerca gregaria ) before measuring jumping performance. Knockdown reduced the amount of resilin-associated fluorescence in the semilunar processes (SLPs) by 44% and reduced the cross-sectional area of the tendons of the hind leg extensor-tibiae muscle by 31%. This affected jumping in three ways: First, take-off velocity was reduced by 15% in knockdown animals, which could be explained by a change in the extrinsic stiffness of the extensor-tibiae tendon caused by the decrease in its cross-sectional area. Second, knockdown resulted in permanent breakages in the hind legs of 29% of knockdown locusts as tested by electrical stimulation of the extensor muscle, but none in controls. Third, knockdown locusts exhibited a greater decline in distance jumped when made to jump in rapid succession than did controls. We conclude that stiff cuticle acts as the principal elastic energy store for insect jumping, while resilin protects these more brittle structures against breakage from repeated use.

Earliest evidence of sedentism in the Antilles: Multiple isotope data from Canímar Abajo, Cuba

The early populations that inhabited the Antilles were traditionally understood as highly mobile groups of hunters/fishers and gatherers. Although more recent data have demonstrated that some populations engaged in the production of domestic plants and cultivars, questions remain about other aspects of their lifeways, including whether the adoption of domesticates was accompanied by a decrease in residential mobility. The level of sedentism in a population is an instrumental variable to understand community social relations and complexity, adaptations, and lifeways. Here, we combined enamel strontium ( 87 Sr/ 86 Sr), oxygen (δ 18 O en ), and carbon (δ 13 C en ) isotopes of 44 human teeth from the site of Canímar Abajo—where the oldest human remains from the insular Caribbean have been reported—to examine the mobility patterns of early Antillean groups. In contrast with traditional narratives, the homogeneous strontium isotope values observed in most individuals from the older funerary area of the site (cal. BC 2237–790) were consistent with the pattern expected for a sedentary population subsisting primarily on local resources obtained close to the coast. The isotopic evidence reveals that between cal. AD 403–1282, the mound was reused for funerary practices by both local communities and nonlocal individuals. The evidence suggests that this period saw higher population mobility, with influxes of individuals from more distant locations and diverse dietary and burial traditions. The isotope results from Canímar Abajo provide the earliest isotopic evidence of populations with low-level residential mobility in the Antilles.

Family relations of Moche elite burials on the North Coast of Peru (~500 CE): Analyses of the Señora de Cao and relatives

The Moche archaeological culture flourished along Peru’s North Coast between the 4th and 10th centuries CE and was characterized by a complex social hierarchy dominated by political and religious elites. Previous archaeological evidence suggests kinship was a key factor in maintaining political authority within Moche society. To test this hypothesis, we applied archaeological, genetic, and isotopic methods to examine familial relationships between six individuals, including the prominent Señora de Cao ( ~500 CE ), buried together in a pyramid-like, painted temple, Huaca Cao Viejo, in the Chicama Valley, Peru. Our findings reveal that all six individuals were biologically related, with varying degrees of kinship. The Señora de Cao was interred with a sacrificed juvenile, identified as a possible niece, and at least one, and potentially two siblings and a grandparent in separate tombs nearby. One of the male siblings was accompanied in death by his sacrificed son. Isotopic analysis indicates that while most individuals had diets rich in maize and animal protein and spent their childhoods in or near the Chicama Valley, the sacrificed juvenile accompanying the Señora had a distinct diet and geographic origin. These results demonstrate that Moche elites were interred with family members, including some raised far from their parental homes. This supports the hypothesis that kinship was central to transmitting status and authority. Moreover, sacrificing family members to accompany deceased elites underscores the significance of ritual sacrifice in reinforcing familial ties and linking the deceased to both ancestors and the divine.

Comparing cooperative geometric puzzle solving in ants versus humans

Biological ensembles use collective intelligence to tackle challenges together, but suboptimal coordination can undermine the effectiveness of group cognition. Testing whether collective cognition exceeds that of the individual is often impractical since different organizational scales tend to face disjoint problems. One exception is the problem of navigating large loads through complex environments and toward a given target. People and ants stand out in their ability to efficiently perform this task not just individually but also as a group. This provides a rare opportunity to empirically compare problem-solving skills and cognitive traits across species and group sizes. Here, we challenge people and ants with the same “piano-movers” load maneuvering puzzle and show that while ants perform more efficiently in larger groups, the opposite is true for humans. We find that although individual ants cannot grasp the global nature of the puzzle, their collective motion translates into emergent cognitive skills. They encode short-term memory in their internally ordered state and this allows for enhanced group performance. People comprehend the puzzle in a way that allows them to explore a reduced search space and, on average, outperform ants. However, when communication is restricted, groups of people resort to the most obvious maneuvers to facilitate consensus. This is reminiscent of ant behavior, and negatively impacts their performance. Our results exemplify how simple minds can easily enjoy scalability while complex brains require extensive communication to cooperate efficiently.

Persistent humid climate favored the Qin and Western Han Dynasties in China around 2,200 y ago

The Qin and Western Han dynasties (221 BCE to 24 CE) represent an era of societal prosperity in China. However, due to a lack of high-resolution paleoclimate records it is still unclear whether the agricultural boost documented for this period was associated with more favorable climatic conditions. Here, multiparameter analysis of annually resolved tree-ring records and process-based physiological modeling provide evidence of stable and consistently humid climatic conditions during 270 to 77 BCE in northern China. Precipitation in the Asian summer monsoon region during the Qin–Western Han Dynasties was ~18 to 34% higher compared to present-day conditions. In shifting agricultural and pastoral boundaries ~60 to 100 km northwestward, possibility up to 200 km at times, persistently wetter conditions arguably increased food production, contributing to the socioeconomic prosperity around 2,200 y ago. A gradual wetting trend in the western part of arid northwestern China since the 1980s resembles the historical climate analogue, suggesting that similar benefits for regional environmental and agricultural systems may reoccur under current climate change, at least in the near term.

The effect of CO ₂ ramping rate on the transient weakening of the Atlantic Meridional Overturning Circulation

The Atlantic Meridional Overturning Circulation (AMOC) is a key component of the global climate that is projected to weaken under future anthropogenic climate change. While many studies have investigated the AMOC’s response to different levels and types of forcing in climate models, relatively little attention has been paid to the AMOC’s sensitivity to the rate of forcing change, despite it also being highly uncertain in future emissions scenarios. In this study, I isolate the AMOC’s response to different rates of CO 2 increase in a state-of-the-art global climate model and find that the AMOC undergoes more severe weakening under faster rates of CO 2 change, even when the magnitude of CO 2 change is the same. I then propose an AMOC-ocean heat transport-sea ice feedback that enhances the decline of the circulation and explains the dependence on the rate of forcing change. The AMOC’s rate-sensitive behavior leads to qualitatively different climates (including differing Arctic sea ice evolution) at the same CO 2 concentration, highlighting how the rate of forcing change is itself a key driver of global climatic change.

Aerosol light absorption alleviates particulate pollution during wintertime haze events

Aerosol light absorption has been widely considered as a contributing factor to the worsening of particulate pollution in large urban areas, primarily through its role in stabilizing the planetary boundary layer (PBL). Here, we report that absorption-dominated aerosol–radiation interaction can decrease near-surface fine particulate matter concentrations ([PM 2.5 ]) at a large-scale during wintertime haze events. A “warm bubble” effect by the significant heating rate of absorbing aerosols above the PBL top generates a secondary circulation, enhancing the upward motion (downward motion) and the convergence (divergence) in polluted (relatively clean) areas, with a net effect of lowering near-surface [PM 2.5 ]. Furthermore, aerosol absorption of ultraviolet-wave light effectively reduces the photolysis of chemical species, i.e., aerosol–photolysis interaction, hindering ozone formation, reducing atmospheric oxidizing capability, and suppressing secondary aerosol concentrations. Our model assessment reveals that the synergetic two effects decrease near-surface [PM 2.5 ] by around 7.4%, so the presence of light-absorbing aerosols can considerably alleviate particulate pollution during wintertime haze events. Such negative feedbacks to the aerosol loading should be considered in weather/climate prediction and health assessment models.

Divergence time and environmental similarity predict the strength of morphological convergence in stick and leaf insects

Independent evolution of similar traits in lineages inhabiting similar environments (convergent or repeated evolution) is often taken as evidence for adaptation by natural selection, and used to illustrate the predictability of evolution. Yet convergence is rarely perfect for two reasons. First, environments may not be as similar as they appear. Second, responses to selection are contingent upon available genetic variation and independent lineages may differ in the alleles, genetic backgrounds, and even the developmental mechanisms responsible for the phenotypes in question. Both impediments to convergence are predicted to increase as the length of time separating two lineages increases, making it difficult to discern their relative importance. We quantified environmental similarity and the extent of convergence to show how habitat and divergence time each contribute to observed patterns of morphological evolution in 212 species of stick and leaf insects (order Phasmatodea). Dozens of phasmid lineages independently colonized similar habitats, repeatedly evolving in parallel directions on a 23-trait morphospace, though the magnitude and direction of these shifts varied. Lineages converging toward more similar environments ended up closer on the morphospace, as did closely related lineages, and closely related lineages followed more parallel evolutionary trajectories to arrive there than more distantly related ones. Remarkably, after accounting for habitat similarity, we show that divergence time reduced the extent of convergence at a constant rate across more than 100 My of separation, suggesting even the magnitude of contingency can be predictable, given sufficient spans of time.

The effect of job loss on risky financial decision-making

Job loss is a common and disruptive life event. It is known to have numerous long-term negative effects on financial, health, and social outcomes. While the negative effects of becoming unemployed on health and well-being are well understood, the influence of job loss on financial decisions has received little attention. Across a large-scale survey ( N = 37 , 854 ), spending data from a bank ( N = 404 , 470 ), and two online experiments (total N = 1 , 403 ), we find that job loss increases financial risk-taking. First, in survey data, job loss is associated with elevated levels of self-reported financial risk-taking and lottery ticket purchases. Next, using administrative data from a large bank, we find consistent causal evidence of the influence of job loss on gambling spending. Although total spending decreases after job loss, gambling spending is less affected than our control categories. Finally, we turn to two incentive-compatible manipulations of job loss operationalized in a lab setting. We find that this experimental manipulation increases the take-up of financial risks. The current finding that job loss increases financial risk-taking could accentuate long-term negative financial effects of job loss.

Fast-chargeable lithium-ion batteries by μ-Si anode-tailored full-cell design

Silicon (Si) anodes have long been recognized to significantly improve the energy density and fast-charging capability of lithium-ion batteries (LIBs). However, the implementation of these anodes in commercial LIB cells has progressed incrementally due to the immense volume change of Si across its full state-of-charge (SOC) range. Here, we report an anode-tailored full-cell design (ATFD), which incorporates micrometer-sized silicon (μ-Si) alone, for operation over a limited, prespecified SOC range identified as 30−70%. This range allows homogeneous (de)lithiation throughout the electrode, accompanied by an acceptable level of volume change. The ATFD-based cell exhibits 21.3% higher gravimetric energy density than that of its graphite-based counterpart in a commercial 18650 cylindrical cell and 84.6% capacity retention after 500 cycles even at a fast-charging rate of 3 C. This study indicates that the partial, intermediate SOC operation of the μ-Si anode can markedly increase the energy density and boost the fast-charging capability of a LIB cell, a challenging task in traditional cell engineering.

Personality differences between birth order categories and across sibship sizes

We examined associations of self-reports on the HEXACO Personality Inventory—Revised (HEXACO-PI-R) with birth order category and sibship size, controlling for participant sex and age. In a first sample ( N > 700,000 online adults, mainly from English-speaking countries), Honesty-Humility and Agreeableness both showed the highest means for middle-borns, followed in order by last-borns (youngests), firstborns (oldests), and only children, with differences between middles and onlys of d ≥ 0.20. The same result was replicated in a similar but smaller second sample ( N > 70,000) in which sibship size was also assessed, thereby allowing birth order differences to be separated from sibship size differences. In that sample, Honesty-Humility and Agreeableness showed higher means with larger sibship sizes, with differences between sibship sizes of 1 and 6+ of d = 0.30 and d = 0.36, respectively. Controls for upbringing religiousness and current religiousness reduced these differences by about 25%. Within sibship sizes, birth order differences in these dimensions were considerably smaller but oldests remained up to d = 0.10 lower than middles and youngests. Openness was d ≈ 0.10 higher for onlys than for non-onlys collectively, and within sibship sizes, Openness was d ≈ 0.10 higher for oldests than for middles and youngests.

Correction for Ritz et al., Social anxiety disorder-associated gut microbiota increases social fear

Correction for Bartesaghi et al., Inhibition of oxidative metabolism leads to p53 genetic inactivation and transformation in neural stem cells

Correction for Armstrong et al., Genetic differentiation and precolonial Indigenous cultivation of hazelnut ( <i>Corylus cornuta</i> , Betulaceae) in western North America

Correction for Yun et al., GPCR targeting of E3 ubiquitin ligase MDM2 by inactive β-arrestin

Correction for Zhou et al., A genome-wide microRNA screen identifies the microRNA-183/96/182 cluster as a modulator of circadian rhythms

Correction for Huo et al., Hierarchical behavior control by a single class of interneurons

Nocturnal camouflage through background matching against moonlight

Camouflage is often considered a daytime phenomenon based on light and shade. Nocturnal camouflage can also occur, but its mechanistic basis remains unclear. Here, we analyze the conditions for background matching (BM) of avian predators against the night sky. Such concealment is achieved when the contrast between the predator and the sky is smaller than the contrast detection threshold of prey. This condition cannot be fulfilled under isotropic skies, as in fully overcast or moonless nights. However, on clear moonlit nights, the isotropy of the sky radiance is broken due to the presence of the Moon, and the conditions for BM can be met for a wide range of sky directions. This effect is mainly dependent on the altitude of the Moon above the horizon, rather than on Moon phase. We have modeled the feasibility of concealment through BM of a typically white barn owl ( Tyto alba ) when hunting rodents, based on its contrast against the moonlit sky. We considered the radiometric quantities of the sky, the ground, and the bird’s undersides. Our results show that a barn owl with highly reflecting underparts may approach a rodent from broad regions of the moonlit sky while keeping itself below the contrast detection threshold of the mouse M-cones and rods. S-cones, in turn, remain below their excitation threshold for most of the lunar cycle. Our results demonstrate that the white color of barn owls serves as camouflage tailored to the moonlit sky background, providing a mechanistic basis for understanding nocturnal camouflage.

<i>Ab initio</i> study of randomly disordered hexagonal close-packed (rhcp) phase in platinum

Platinum is one of the most important technological materials, and one of the most studied transition metals. Yet, its phase diagram remains virtually unknown. The solid phase of Pt at ambient conditions is face-centered cubic (fcc). However, in a previous paper [L. Burakovsky et al., J. Phys. Conf. Ser. 500, 162001 (2014)], we predicted Pt to undergo a phase transformation from fcc to another solid phase, namely, randomly disordered hexagonal close-packed (hcp) or simply random hcp (rhcp), which spans a pressure interval of ∼35–300 GPa and exists at temperatures ∼&amp;gt;3000 K. Since then, rhcp-Pt has been widely discussed in the literature but has been neither confirmed experimentally nor completely ruled out theoretically. In this work, using the technique of three-phase ab initio quantum molecular dynamics (QMD) simulations, we demonstrate the appearance of rhcp-Pt and determine the phase boundary that separates rhcp from fcc on the Pt phase diagram. These three-phase simulations consist in evolving a system containing two different hexagonal polytypes separated by liquid until the system reaches its final equilibrium state. It then appears that the results of the most recent experimental study on Pt melting, by Geballe et al. [Phys. Rev. Mater. 5, 033803 (2021)], map out a curve identified by Geballe et al. as the Pt melting curve, which virtually coincides with the fcc-rhcp solid–solid phase boundary presented in our work. We discuss the reasons for misinterpreting the fcc-rhcp solid–solid phase transition as melting. We calculate the equation of state (EOS) of fcc-Pt and refine its melting curve via more accurate QMD simulations using the Z method implemented with Vienna Ab initio Simulation Package. We also calculate the EOS and melting curve of rhcp-Pt. The two melting curves, along with the fcc-rhcp phase boundary, define the ab initio phase diagram of Pt that we present here. Our results extend the pressure range of rhcp-Pt by more than twice compared to the original result of 2014, namely, to ∼50–650 GPa. Finally, we argue that, despite being polymorphic, Pt should be considered as reliable EOS and shock-wave standards.

Multicaloric effect in FeRh, exploiting the thermal hysteresis in a multi-stimuli cycle combining pulsed magnetic field and uniaxial load

Large magnetocaloric effects can be observed in materials with first-order magneto-structural phase transition. However, materials with large thermal hysteresis show a reduced effect in moderate fields (∼2 T) because the external field is insufficient to induce a fully reversible transformation. The hysteresis can be overcome or even exploited by applying a second external stimulus. A multi-stimuli test bench has been built to demonstrate the multicaloric effect in FeRh alloy using a pulsed magnetic field up to 9 T and a uniaxial stress of up to 700 MPa. A cyclic multicaloric effect of ±2.5 K could be observed for a sequential application of a pulsed field of 3 T and a uniaxial stress of 700 MPa. The interplay among external field strength, thermal hysteresis, and the transition width enables the use of pulsed magnetic fields and allows a decoupling of the applied magnetic field and the heat transfer process in the multi-stimuli cycle.