The expansion of Digital Health brings increasing data privacy and security challenges, mainly due to data collection by service providers and third parties. The decentralized approach of Self-Sovereign Identity emerges as a solution, offering users direct control over their data. This paper proposes the SmartMed system for controlling access to private medical data by attribute-based access control implemented on smart contracts. The paper investigates the performance limitations of the Ethereum, Besu, and Hyperledger Fabric blockchain platforms in controlling access to medical data. The proposal develops smart contracts to perform attribute-based access control and to store log records on the blockchain, highlighting the detailed performance analysis on both tested platforms. The results reveal the superiority of the Hyperledger Fabric platform over Ethereum and Besu, indicating a higher transaction throughput. Our proposal innovates by proposing a system based on smart contracts to guarantee the authenticity of medical data, complemented by the use of Keycloak in managing access to healthcare systems.

In this work, we explored theoretically the spatial resolution of magnetic solitons and the variations of their sizes when subjected to a magnetic force microscopy (MFM) measurement. Next to tip-sample separation, we considered reversal in the magnetization direction of the tip, showing that the magnetic soliton size measurement can be strongly affected by the magnetization direction of the tip. In addition to previous studies that only consider thermal fluctuations, we developed a theoretical method to obtain the minimum observable length of a magnetic soliton and its length variation due to the influence of the MFM tip by minimizing the soliton’s magnetic energy. We show that a simple spherical model for the MFM tip can capture most of the physics underlying tip-sample interactions, with the key requirement being an estimate of the magnetization field within the sample. Our model uses analytical and numerical calculations and prevents overestimating the characteristic length scales from MFM images. We compared our method with available data from MFM measurements of domain wall widths, and we performed micromagnetic simulations of a skyrmion-tip system, finding a good agreement for both attractive and repulsive domain wall profile signals and for the skyrmion diameter in the presence of the magnetic tip. In addition, the theoretically calculated frequency shift presents good qualitative agreement with experimental measurements. Our results provide significant insights for a better interpretation of MFM measurements of different magnetic solitons and will be helpful in the design of potential reading devices based on magnetic solitons as information carriers.

The COVID-19 pandemic has highlighted the necessity for agile health services that enable reliable and secure information exchange, but achieving proper, private, and secure sharing of EMRs remains a challenge due to diverse data formats and fragmented records across multiple data silos, resulting in hindered coordination between healthcare teams, potential medical errors, and delays in patient care. While centralized EMR systems pose privacy risks and data format diversity complicates interoperability, blockchain technology offers a promising solution by providing decentralized storage, ensuring data integrity, enhancing access control, eliminating intermediaries, and increasing efficiency in healthcare. By focusing on a Brazilian case study, this paper explores the significance of EMR standards, security challenges, and blockchain-based approaches to promote interoperability and secure data sharing in the healthcare industry.