Distributed ledgers – decentralized databases maintained by network consensus – are often modeled as directed acyclic graphs (DAGs) to capture the causal structure of data addition. Although blockchain systems like Bitcoin use linear chains, alternatives such as tangle in IOTA employ random DAGs. In such mechanisms each new transaction approves multiple predecessors selected through a randomized process. Prior work has established a fluid-limit approximation of the tangle’s growth, governed by a delay differential equation. In this paper we go beyond the fluid limit by analyzing the next-order behavior. We show that the fluctuations around the deterministic limit converge to a Gaussian process and derive a stochastic delay differential equation (SDDE) that describes this next-order approximation.

In recent years, the through-wall imaging (TWI) systems have garnered tremendous interest due to their potential applications in surveillance, search–rescue operations, and security monitoring, enabling the detection and visualization of objects behind opaque obstacles such as walls. The multiple-input multiple-output (MIMO) TWI system has been developed to detect hidden targets behind walls. MIMO-based TWI considerably reduces the time it takes to scan the walls. This study presents an experimental evaluation of a MIMO-based TWI system using a dataset of targets with varying dielectric properties placed at uniform and nonuniform distances behind a wall. The B-scan data are collected for different types of targets for contrast target detection. To effectively suppress clutter and enhance target detectability, we employed a range of advanced signal processing techniques, including singular value decomposition (SVD), SVD-based noise subspace exploitation, the optimum shrinkage algorithm, and background subtraction using data-driven thresholding. The target-to-clutter ratio of the final image was computed to evaluate the effectiveness of each clutter removal technique and to facilitate a comparative analysis of the results. The imaging results demonstrated that the system could detect single and multiple targets, including those composed of different materials.

This article reinterprets the reverse of the Codex Cospi, a Postclassic Central Mexican manuscript. Challenging long-standing views that the iconography in its plates refers to hunting rituals or protective ceremonies against poisonous animals, the article argues that they instead record ritual protocols for the presentation of offerings to divine effigies enshrined in temples. Through a comparison with other codices, archaeological data, and historical sources, the article proposes that the anthropomorphic figures depict temple images of deities, while the surrounding elements encode offerings of blood, aromatic, and coloring substances intended to be deposited before these images in prescribed quantities and sequences. Situating this imagery within Mesoamerican practices of communication with the divine, the article suggests that the reverse of the Codex Cospi functioned as a ritual manual complementing its divinatory obverse. Finally, it considers the possibility that the reverse has been produced in the workshop of a modest, possibly rural community, thereby illuminating the social context of this rare manuscript.

Microwave hyperthermia (HT) is a promising adjunct therapy for breast tumors. This study investigates gold nanoparticle (GNP)-enhanced HT through three-dimensional electromagnetic (EM) simulation of a realistic breast phantom containing an embedded 5 mm tumor, excited by an eight-element fractal octagonal ring antenna (FORA) array operating at 2.45 GHz. A 5.85 nM concentration of 21 nm peptide-capped GNPs confined to the tumor region produces a 65–75$\%$ increase in peak specific absorption rate (SAR) and improves the target-to-breast quotient by 39–47$\%$ across both optimization methods, without introducing additional hotspots in healthy tissue. Two complementary optimization strategies are compared: Python-based genetic algorithm (GA) post-processing and direct optimization within CST. The Python/GA approach achieves a six- to seven-fold reduction in computational time (22–24 vs. 145–158 minutes), enabling rapid treatment planning for varying tumor geometries and nanoparticle concentrations. Baseline thermal modeling confirms that tumor temperatures reach 43–45$^\circ$C, within the therapeutic window for HT. These results demonstrate that GNPs effectively enhance EM energy focusing within the tumor region. The FORA antenna delivers the microwave energy, while the GNPs modify the target’s dielectric profile to selectively boost energy absorption-confining the heat to the tumor while safeguarding adjacent healthy tissue.’ Overall, this work provides computational evidence supporting the feasibility of GNP-enhanced microwave HT, while highlighting key optimization trade-offs between computational efficiency and protection of healthy tissue.

Continually confronted with myriad threats, transnational drug-trafficking organizations (TDTOs) employ different strategies to mitigate risk. In this article, we focus on the political consequences of these risk-mitigation strategies, and offer a theoretical framework through which to understand them. We start from the premise that TDTOs are not inherently political actors. Nonetheless, as illegal enterprises with access to considerable financial resources, TDTOs are (if often inadvertently) capable of shaping politics in important ways if and when they invest in protection, provided by both state and nonstate actors. When these trafficking groups invest in protection, they are capable, firstly, of determining who is able to access political power and, secondly, of affecting how political power is exercised, reshaping the institutions used to govern society—though above all at the subnational level. We provide illustrative evidence for our framework from the Colombian city of Medellín.

Transcatheter closure is the preferred treatment for type 2 atrial septal defects. Device retrieval for embolisation or malpositioning is rarely necessary and can often be performed percutaneously. However, transcatheter retrieval of Occlutech Figulla Flex II atrial septal defects occluders >16 mm can be very difficult, and it has even been stated to be impossible in the literature. Its right atrial hub is ball shaped so that snare devices could slip off when retrieving a large device into a sheath, necessitating the use of multiple snare or other retrieval devices. We present three paediatric cases (four procedures in total) of successful > 16 mm Occlutech atrial septal defect occluder retrieval using a single Multi-Snare® device.

The paper proposes a multiband ultra-wideband adaptive antenna with a deep recurrent neural network long short-term memory (RNN-LSTM) algorithm to enable reliable telemetry for implantable pacemakers. It is proposed that electromagnetic optimization can be combined with data-driven adaptation in the proposed design in order to ensure stable resonance and low signal distortion under different tissue conditions. A 2.4 and 5.8–9 GHz compact fractal patch antenna in biocompatible polycarbonate material is fabricated to provide high efficiency and low specific absorption rate of its radiation. The RNN-LSTM network is able to predict time-varying impedance drift and apply the adaptive retuning of antenna parameters in a closed-loop control loop to allow communication over long durations with low latency. Electromagnetic modeling does verify a return loss of −41.2, a 6.5 dBi gain, radiation efficiency of 88, and an Alexander report of 0.72 W/kg to be within the safety thresholds of IEEE C95.1. The smart feedback system offers 99% telemetry error and latency of under 8 ms improvements, compared with the conventional methods of tuning that are static. The findings show that the proposed hybrid solution would greatly boost signal integrity, safety, and energy usage, which is a viable breakthrough to the next generation of adaptable biomedical communication systems.

Timed to coincide with the two hundred and fiftieth anniversary of the Declaration of Independence that launched a revolution that created the United States of America, this series of articles complicates traditional narratives of this transformative event by situating it in a larger British world context.

This article considers the significance of the US Declaration of Independence in the western hemisphere. It argues first that the influence of the Declaration was limited in an era we call “the age of imperial fracture.” Second, it contends that the former colonies that achieved independence, including the United States, did not experience a sharp break with the past. Instead, they grappled with the legacies of colonialism and imperial ambitions. Throughout the western hemisphere, independence triggered new waves of contestation and conflict and gave rise to new forms of imperialism.