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We study the orientation in a uniform magnetic field of rod-like anisotropic biofluid crystals with an easy plane that makes an oblique angle with the crystal's c-axis. For a sufficiently strong field, these crystalline rods orient themselves such that the crystal's easy plane is parallel to the magnetic field, the rod's direction being defined as the direction of the crystal's c-axis. As the rod rotates about the crystal's hard axis there will therefore be a range of angles that the rod makes with the magnetic field. We detail this behavior by first providing illustrations of hemozoin crystals at various orientations. These illustrations clearly demonstrate that the orientation angle that the crystalline rod makes with respect to the magnetic field varies from about 30 deg to 150 deg. We also derive an analytical expression for the probability density function for the orientation angle. We find that the orientation angles are not uniformly distributed between the limits of 30 deg and 150 deg, but rather tend to cluster near these limits. This suggests experimental tests and addresses confusion about the rod orientation found in past literature. The relevance to other anisotropic biofluid crystals, such as those produced by gout, is also discussed., Comment: 12 pages, 6 figures

Evidence to guide healthcare decisions is often limited by a lack of relevant and trustworthy literature as well as difficulty in contextualizing existing research for a specific patient. Large language models (LLMs) could potentially address both challenges by either summarizing published literature or generating new studies based on real-world data (RWD). We evaluated the ability of five LLM-based systems in answering 50 clinical questions and had nine independent physicians review the responses for relevance, reliability, and actionability. As it stands, general-purpose LLMs (ChatGPT-4, Claude 3 Opus, Gemini Pro 1.5) rarely produced answers that were deemed relevant and evidence-based (2% - 10%). In contrast, retrieval augmented generation (RAG)-based and agentic LLM systems produced relevant and evidence-based answers for 24% (OpenEvidence) to 58% (ChatRWD) of questions. Only the agentic ChatRWD was able to answer novel questions compared to other LLMs (65% vs. 0-9%). These results suggest that while general-purpose LLMs should not be used as-is, a purpose-built system for evidence summarization based on RAG and one for generating novel evidence working synergistically would improve availability of pertinent evidence for patient care., Comment: 28 pages (2 figures, 3 tables) inclusive of 8 pages of supplemental materials (4 supplemental figures and 4 supplemental tables)

In view of the growing role of magnetic particles under magnetic field influence in medical and other applications, and perforce the bead chaining, it is important to understand more generally the chain dynamics. As is well known, in the presence of a magnetic field, magnetic beads tend to form chains that are aligned with the magnetic field vector. In addition, if there is a magnetic field gradient, there will be a magnetic force acting on this chain. The main goal of the present research is to study the motion of a magnetic bead chain that makes an arbitrary angle with the magnetic force vector in the Stokes flow limit, that is, in the limit of zero Reynolds number. We used the public-domain computer program HYDRO++ to calculate the mobility matrix, which relates the magnetic force acting on the chain to the velocity of the chain, for a chain of N beads making an arbitrary angle with the magnetic force vector. Because of the presence of off-diagonal elements of the mobility matrix, as the chain is drawn in the direction of the magnetic force, it is also deflected to the side. We derived analytic solutions for this motion. Also, for bead chains moving in directions both parallel and perpendicular to their lengths, we fit three-parameter functions to solutions from HYDRO++. We found the fits to be excellent. Combining these results with the analytic solutions, we obtained expressions for the velocity components for the bead chains that provide excellent fits to HYDRO++ solutions for arbitrary angles. Finally, we apply the methodology used for the bead chain studies to the study of an obliquely falling rod in a viscous fluid and derive analytic solutions for the velocity components of the obliquely falling rod., Comment: 21 pages, 8 figures, Accepted for publication in PLOS ONE, April 2, 2024