arXiv subjects

Hiromasa Ito

Publications and source records attributed to Hiromasa Ito.

4 recordsLinked to original sources

arXiv2026

High-Fidelity Longitudinal Patient Simulation Using Real-World Data

Simulation is a powerful tool for exploring uncertainty. Its potential in clinical medicine is transformative and includes personalized treatment planning and virtual clinical trials. However, simulating patient trajectories is challenging because of complex biological and sociocultural influences. Here, we show that real-world clinical records can be leveraged to empirically model patient timelines. We developed a generative simulator model that takes a patient's history as input and synthesizes fine-grained, realistic future trajectories. The model was pretrained on more than 200 million clinical records. It produced high-fidelity future timelines, closely matching event occurrence rates, laboratory test results, and temporal dynamics in real patient future data. It also accurately estimated future event probabilities, with observed-to-expected ratios consistently near 1.0 across diverse outcomes and time horizons. Our results reveal the untapped value of real-world data in electronic health records and introduce a scalable framework for in silico modeling of clinical care.

cs.AI↗

arXiv2026

Generating Counterfactual Patient Timelines from Real-World Data

Counterfactual simulation - exploring hypothetical consequences under alternative clinical scenarios - holds promise for transformative applications such as personalized medicine and in silico trials. However, it remains challenging due to methodological limitations. Here, we show that an autoregressive generative model trained on real-world data from over 300,000 patients and 400 million patient timeline entries can generate clinically plausible counterfactual trajectories. As a validation task, we applied the model to patients hospitalized with COVID-19 in 2023, modifying age, serum C-reactive protein (CRP), and serum creatinine to simulate 7-day outcomes. Increased in-hospital mortality was observed in counterfactual simulations with older age, elevated CRP, and elevated serum creatinine. Remdesivir prescriptions increased in simulations with higher CRP values and decreased in those with impaired kidney function. These counterfactual trajectories reproduced known clinical patterns. These findings suggest that autoregressive generative models trained on real-world data in a self-supervised manner can establish a foundation for counterfactual clinical simulation.

cs.LG↗

arXiv2017

X-ray study of extended emission around M86 observed with Suzaku

We analyzed the Suzaku data of M86 and its adjacent regions to study the extended emission around it. The M86 core, the plume, and the tail extending toward the northwest were clearly detected, as well as the extended halo around them. From the position angle $\sim45°$ to $\sim275°$, the surface brightness distribution of the core and the extended halo was represented relatively well with a single $β$-model of $β\sim0.5$ up to 15'-20'. The X-ray spectra of the core was represented with a two-temperature model of $kT\sim 0.9$ keV and $\sim0.6$ keV. The temperatures of the core and the halo have a positive gradient in the center, and reach the maximum of $kT\sim1.0$ keV at $r\sim7'$, indicating that the halo gas is located in a larger scale potential structure than that of the galaxy. The temperatures of the plume and the tail were $0.86\pm0.01$ keV and $1.00\pm0.01$ keV. We succeeded in determining the abundances of $α$-element separately, for the core, the plume, the tail, and the halo for the first time. Abundance ratios with respect to Fe were consistent with the solar ratios everywhere, except for Ne. The abundance of Fe was $\sim0.7$ in the core and in the plume, while that in the tail was $\sim1.0$, but the difference was not significant considering the uncertainties of the ICM. The abundance of the halo was almost the same up to $r\sim10'$, and then it becomes significantly smaller (0.2-0.3) at $r\gtrsim10'$, indicating the gas with low metal abundance still remains in the outer halo. From the surface brightness distribution, we estimated the gas mass ($\sim3\times10^{10}M_\odot$) and the dynamical mass ($\sim3\times10^{12}M_\odot$) in $r<100$~kpc. The gas mass to the dynamical mass ratio was $10^{-3}$-$10^{-2}$, suggesting a significant fraction of the halo gas has been stripped.

astro-ph.HE↗

arXiv2010

Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, we show how to retrieve the complex polarization dependent refractive index of the composite films. We then detail the selfconsistent algorithm for retrieving the optical properties of the metal alloy used in the fabrication of the metamaterial layers by using an effective medium approximation. Finally, we study challenges in fabrication of metamaterials with sub-micrometer metallic wires by repeated stack-and-draw process by comparing samples made using 2, 3 and 4 consecutive drawings. When using metallic alloys we observe phase separation effects and nano-grids formation on small metallic wires.

physics.optics↗