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Phase change materials (PCMs) have tremendous capacity as passive components to recover and repurpose thermal energy from transient power systems. However, PCMs are only effective if the time scale of the thermal energy storage and retrieval rates match those required for a particular system. We develop a framework to assess the efficiency of pulsed thermal energy storage based on the concept of “thermal impedance,” drawing upon an analogous approach from electrical energy storage. We experimentally characterize a 1 cm thick paraffin-infiltrated copper foam composite PCM subject to pulsed heat boundary conditions up to 1 W cm−2 and demonstrate a decrease in thermal impedance by up to a factor of 2.5× in the regime in which melting occurs (τon = 10−1 to >102 s) relative to a reference case in which melting does not occur. This represents both a signature of the ability to extract or retrieve thermal energy via latent heat, as well as an experimentally accessible measure that provides insight into the internal dynamics of a composite PCM volume. These principles can serve to design the internal structure of composite PCM elements for pulsed thermal systems. 

Abstract Binary neutron star mergers can produce extreme magnetic fields, some of which can lead to strong magnetar-like remnants. While strong magnetic fields have been shown to affect the dynamics of outflows and angular momentum transport in the remnant, they can also crucially alter the properties of nuclear matter probed in the merger. In this work, we provide a first assessment of the latter, determining the strength of the pressure anisotropy caused by Landau-level quantization and the anomalous magnetic moment. To this end, we perform the first numerical relativity simulation with a magnetic polarization tensor and a magnetic-field-dependent equation of state using a new algorithm we present here, which also incorporates a mean-field dynamo model to control the magnetic field strength present in the merger remnant. Our results show that—in the most optimistic case—corrections to the anisotropy can be in excess of 10% and are potentially largest in the outer layers of the remnant. This work paves the way for a systematic investigation of these effects. 

For densities beyond nuclear saturation, there is still a large uncertainty in the equations of state (EoSs) of dense matter that translate into uncertainties in the internal structure of neutron stars. The MUSES Calculation Engine provides a free and open-source composable workflow management system, which allows users to calculate the EoSs of dense and hot matter that can be used, e.g., to describe neutron stars. For this work, we make use of two MUSES EoS modules, i.e., Crust Density Functional Theory and Chiral Mean Field model, with beta-equilibrium with leptons enforced in the Lepton module, then connected by the Synthesis module using different functions: hyperbolic tangent, generalized Gaussian, bump, and smoothstep. We then calculate stellar structure using the QLIMR module and discuss how the different interpolating functions affect our results. 

Synopsis Seventy percent of mammals copulate using repeated pelvic thrusting, while the transfer of sperm requires just a single intromission. Why did thrusting evolve to be the dominant form of sexual intercourse? In this study, we investigate how the rate of sexual pelvic thrusting changes with body size. By analyzing films of copulating mammals, from mice Mus musculus to elephants Elephantidae, we find that bigger animals thrust slower. The rate of pelvic thrusting decreases from 6 Hz for the pocket mouse Pergonathus to 1.3–1.8 Hz for humans to an absence of thrusting for the rhino Rhinocerotidae and elephant Elephantidae families. To understand this dependence on body size, we consider the spring-like behavior of the legs, which is associated with the elasticity of the body's muscles, tendons, and ligaments. For both running and thrusting, greater displacment and energy savings can be achieved if the system is oscillated at its resonant or natural frequency. Resonant frequencies, as measured through previous studies of running in dogs Canis familiaris and horses Equus ferus caballus, show good agreement with sexual thrusting frequencies. Running and sexual thrusting have nothing in common from a behavioral perspective, but from a physical perspective, they are both constrained by the same musculoskeletal systems, and both take advantage of resonance. Our findings may provide improved treatments for human sexual dysfunction as well as improving breeding strategies for domestic mammals. 

Social norms on household energy consumption practices have been historically fostered through ideas of comfort, cleanliness and modernity, underpinned by reliable and affordable energy services. Contemporary discourses on energy transitions require households to conform to new expectations of “sustainable” living, calling for energy users to participate in the electrification of energy end-uses, provided sufficient economic incentives. Yet, a combination of emotional and social responses to the increased frequency of power outages complicate this account. Despite expectations of consumer cooperation in the clean energy transition, limited research explores how differing capabilities and lived experiences with energy infrastructure modify perspectives on these changes. Through semi-structured interviews with sixty Northern California residents, we explore how residents cope with energy unreliability and whether—or how—they envision transitioning to higher levels of electrification of their homes. By centering users' lived experiences, this work goes beyond formulations of “customer choices” to focus on how everyday energy practices are reimagined in the context of residential electrification policies, climate imperatives, and power outages —or the fear thereof. We argue that the emotional, social, and relational dimensions of grid reliability should complement the predominantly techno-economic lens through which electricity reliability is studied, highlighting the implications of this framing for electricity-intensive residential energy transitions. 

Pretesting—asking learners to try to answer questions about a topic before learning—results in better memory of that topic compared to simply studying the topic without taking a pretest. We investigated whether age and memory contentment moderate the benefit of pretesting, and whether judgments of pretesting effectiveness varied across adulthood (N = 273, age range: 18-82). The pretesting effect was not moderated by either factor. Metacognitive judgments, however, varied by age. Younger participants were more likely to appreciate the benefits of pretesting than middle-aged and older adults. In Study 2 (N = 296, age range: 18-83), our mixed-methods approach showed converging results: The older the participant, the less likely they were to appreciate the benefits of errors and think that pretesting would be effective for them. These results suggest that although the pretesting effect appears to be robust throughout adulthood, metacognitive beliefs differ. 

Abstract Arctic Indigenous food systems are essential to the survival of local communities, but face significant challenges due to environmental, economic, and social pressures. The objective of this study is to elicit values of the mixed Indigenous food system on St. Paul Island, Alaska, and understand their potential as deep leverage points for transformative change in the context of their historical co-evolution with the local food system. To achieve this objective, we engage three generational groups within the Aleut Community of St. Paul Island to obtain local food system stories. From these stories, we (i) elicit historical events that are thought to have shaped the local food system, (ii) identify factors that influence the food system in its present and future states, and (iii) delineate intrinsic, instrumental, and relational food system values. Our findings show that most identified historical events are perceived to have undermined the Indigenous food system and that most factors identified to shape present and future food system states present barriers for community members to engage in traditional practices. Yet, despite this, values that relate to traditional Indigenous livelihoods remain central in the local value system. These results suggest a value change debt, i.e., a time lag between changes in peoples’ held values following changes in the system around them. We propose that this lag provides a window of opportunity to leverage transformative change. We argue that as long as traditional food system values persist, there is potential to reconfigure the food system in a way that embraces these values, enhancing the system's relevance to the community's way of life.