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Abstract Marine fish precipitate carbonates in their intestines that they subsequently excrete as part of an osmoregulatory strategy. While fish carbonates are proposed to be volumetrically significant to the global carbonate budget, no study has presented direct evidence of fish carbonates in the open ocean. Here we examine sediment trap material collected by the Oceanic Flux Program (OFP) in the North Atlantic and observe the episodic occurrence of enigmatic blue particles since 1992. The blue particles are comprised of calcite with unusually high magnesium content (up to 46 mol%) with distinctively depleted δ¹³C and enriched δ¹⁸O compared with calcite produced by common marine calcifiers. Based on the mineralogical, isotopic, and textural similarities between the blue particles and fish carbonates, we propose that the blue particles are produced by pelagic fish. Our data suggest that fish modify their intestinal fluids to create a concentrated, highly supersaturated,¹³C depleted solution capable of precipitating calcite with high magnesium content and low δ¹³C. Collectively, our data imply that fish carbonate production is an open‐ocean phenomenon, opening up the possibility that fish contribute to the production, dissolution, and export of carbonates globally. 

Abstract Kerr microcombs have drawn substantial interest as mass-manufacturable, compact alternatives to bulk frequency combs. This could enable the deployment of many comb-reliant applications previously confined to laboratories. Particularly enticing is the prospect of microcombs performing optical frequency division in compact optical atomic clocks. Unfortunately, it is difficult to meet the self-referencing requirement of microcombs in these systems owing to the approximately terahertz repetition rates typically required for octave-spanning comb generation. In addition, it is challenging to spectrally engineer a microcomb system to align a comb mode with an atomic clock transition with a sufficient signal-to-noise ratio. Here we adopt a Vernier dual-microcomb scheme for optical frequency division of a stabilized ultranarrow-linewidth continuous-wave laser at 871 nm to an ~235 MHz output frequency. This scheme enables shifting an ultrahigh-frequency (~100 GHz) carrier-envelope offset beat down to frequencies where detection is possible and simultaneously placing a comb line close to the 871 nm laser—tuned so that, if frequency doubled, it would fall close to the clock transition in¹⁷¹Yb⁺. Our dual-comb system can potentially combine with an integrated ion trap towards future chip-scale optical atomic clocks. 

In the rapidly growing consumer electronics industry, continuous innovation drives increasing demand for smart devices and advanced gadgets. However, this sector faces changing demands and complex supply chains due to the management of rapid technological advancements and consumer expectations. Seamless communication between suppliers and consumers is essential to optimize production processes, minimize waste, and enhance overall customer satisfaction. In response to these demands, this paper presents a solution that combines Digital Twins (DT) and blockchain to improve security and efficiency in metaverse-inspired consumer-oriented supply chains. Herein, DT is used to represent products in virtual spaces and blockchain secures sensitive information using encryption and access controls. Our objective is to create a transparent, secure, and user-friendly system where consumers and suppliers can interact in real-time to verify product details and access important information of featured tasks like warranties and payment settlement. Smart contracts automates these tasks to make processes faster and more reliable. Through experiments, we tested how well the system maintains product integrity, authenticates transactions, and supports consumer-oriented supply chain (CSC) operations. Comparative analysis shows that our approach improves security, performance, and scalability over existing methods. Furthermore, the proposed system not only enhances security, trust, and transparency in CSC but also sets a higher standard for consumer demands and satisfaction. The findings point to the potential solution for future innovations in metaverse-driven CSC management systems. 

In the era of pervasive digital connectivity, intelligent surveillance systems (ISS) have become essential tools for ensuring public safety, protecting critical infrastructure, and deterring security threats in various environments. The current state of these systems heavily relies on the computational capabilities of mobile devices for tasks such as real-time video analysis, object detection, and tracking. However, the limited processing power and energy constraints of these devices hinder their ability to perform these tasks efficiently and effectively. The dynamic nature of the surveillance environment also adds complexity to the task-offloading process. To address this issue, mobile edge computing (MEC) comes into play by offering edge servers with higher computational capabilities and proximity to mobile devices. It enables ISS by offloading computationally intensive tasks from resource-constrained mobile devices to nearby MEC servers. Therefore, in this paper, we propose and implement an energy-efficient and cost-effective task-offloading framework in the MEC environment. The amalgamation of binary and partial task-offloading strategies is used to achieve a cost-effective and energy-efficient system. We also compare the proposed framework in MEC with mobile cloud computing (MCC) environments. The proposed framework addresses the challenge of achieving energy-efficient and cost-effective solutions in the context of MEC for ISS. The iFogSim simulator is used for implementation and simulation purposes. The simulation results show that the proposed framework reduces latency, cost, execution time, network usage, and energy consumption. 

Abstract Recent demand for distributed software had led to a surge in popularity in actor‐based frameworks. However, even with the stylized message passing model of actors, writing correct distributed software is still difficult. We present our work on linearizability checking in DS2, an integrated framework for specifying, synthesizing, and testing distributed actor systems. The key insight of our approach is that often subcomponents of distributed actor systems represent common algorithms or data structures (e.g., a distributed hash table or tree) that can be validated against a simple sequential model of the system. This makes it easy for developers to validate their concurrent actor systems without complex specifications. DS2 automatically explores the concurrent schedules that system could arrive at, and it compares observed output of the system to ensure it is equivalent to what the sequential implementation could have produced. We describe DS2's linearizability checking and test it on several concurrent replication algorithms from the literature. We explore in detail how different algorithms for enumerating the model schedule space fare in finding bugs in actor systems, and we present our own refinements on algorithms for exploring actor system schedules that we show are effective in finding bugs. 

The effect of oxygen reduction on the magnetic properties of LaFeO3−δ (LFO) thin films was studied to better understand the viability of LFO as a candidate for magnetoionic memory. Differences in the amount of oxygen lost by LFO and its magnetic behavior were observed in nominally identical LFO films grown on substrates prepared using different common methods. In an LFO film grown on as-received SrTiO3 (STO) substrate, the original perovskite film structure was preserved following reduction, and remnant magnetization was only seen at low temperatures. In a LFO film grown on annealed STO, the LFO lost significantly more oxygen and the microstructure decomposed into La- and Fe-rich regions with remnant magnetization that persisted up to room temperature. These results demonstrate an ability to access multiple, distinct magnetic states via oxygen reduction in the same starting material and suggest LFO may be a suitable materials platform for nonvolatile multistate memory.