Crystallization of Brownian particles in thin systems constrained by walls

Keeping formation of a colloidal crystal by a centrifugal force in mind, we carry out Brownian dynamics simulations in thin systems and study ordering of particles induced by an external force. During solidification, the two-dimensional ordering along walls initially occurs. Then, the ordered particles on the walls act as substrates, and crystallization proceeds into bulk. When the external force is weak, the close-packed face of the crystal structure is parallel to the bottom wall. The direction of the close-packed face depends on the strength of the external force: The close-packed face becomes parallel to the side walls with a strong external force

Analysis of the cost‐effectiveness of proton beam therapy for unresectable pancreatic cancer in Japan

Abstract Background Proton beam therapy (PBT) has recently been included in Japan's social health insurance benefits package. This study aimed to determine the cost‐effectiveness of PBT for unresectable, locally advanced pancreatic cancer (LAPC) as a replacement for conventional photon radiotherapy (RT). Methods We estimated the incremental cost‐effectiveness ratio (ICER) of PBT as a replacement for three‐dimensional conformal RT (3DCRT), a conventional photon RT, using clinical evidence in the literature and expense complemented by expert opinions. We used a decision tree and an economic and Markov model to illustrate the disease courses followed by LAPC patients. Effectiveness was estimated as quality‐adjusted life years (QALY) using utility weights for the health state. Social insurance fees were calculated as the costs. The stability of the ICER against the assumptions made was appraised using sensitivity analyses. Results The effectiveness of PBT and 3DCRT was 1.67610615 and 0.97181271 QALY, respectively. The ICER was estimated to be ¥5,376,915 (US$46,756) per QALY. According to the suggested threshold for anti‐cancer therapy from the Japanese authority of ¥7,500,000 (US$65,217) per QALY gain, such a replacement would be considered cost‐effective. The one‐way and probabilistic sensitivity analyses demonstrated stability of the base‐case ICER. Conclusion PBT, as a replacement for conventional photon radiotherapy, is cost‐effective and justifiable as an efficient use of finite healthcare resources. Making it a standard treatment option and available to every patient in Japan is socially acceptable from the perspective of health economics