Neural Network-Based Simulation Method to Examine Ion Behaviors Under Electric Fields: Application to Ion Migration in Amorphous Li3PO4

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MIBG Predicts Falls in PD

Background: Falls are associated with poor prognosis in patients with Parkinson's disease (PD). Although several factors related to falls were reported in patients with PD, objective predictors of falls are not identified. We aimed to determine whether 123I-meta-iodobenzylguanidine (MIBG) cardiac scintigraphy could be a useful biomarker to predict falls. Methods: Forty-five patients with PD were enrolled in this study. These subjects were followed up more than 5 years after MIBG scintigraphy and were divided into two groups: one with decreased uptake of MIBG and the other without decreased uptake of MIBG. The cut-off value for the delayed heart-to-mediastinum ratio was 1.8. Kaplan-Meier analysis and a log-rank test were performed to test the predictive power of MIBG cardiac scintigraphy for falls. Univariate analysis was selected because we did not have appropriate data for adjustment, such as motor and cognitive assessment. Results: The group with decreased uptake of MIBG had a significantly higher incidence of falls than that without decreased uptake of MIBG (P = 0.022, log-rank test). Conclusions: Although the limitations of this study were lack of several key factors including motor and cognitive assessment, MIBG cardiac scintigraphy may be used to predict falls in patients with PD

Prediction of Born effective charges using neural network to study ion migration under electric fields: applications to crystalline and amorphous Li3PO4

Understanding ionic behaviour under external electric fields is crucial to develop electronic and energy-related devices using ion transport. In this study, we propose a neural network (NN) model to predict the Born effective charges of ions along an axis parallel to an applied electric field from atomic structures. The proposed NN model is applied to Li3PO4 as a prototype. The prediction error of the constructed NN model is 0.0376 /atom. In combination with an NN interatomic potential, molecular dynamics (MD) simulations are performed under a uniform electric field of 0.1 V/Å, whereby an enhanced mean square displacement of Li along the electric field is obtained, which seems physically reasonable. In addition, the external forces along the direction perpendicular to the electric field, originating from the off-diagonal terms of the Born effective charges, are found to have a nonnegligible effect on Li migration. Finally, additional MD simulations are performed to examine the Li motion in an amorphous structure. The results reveal that Li migration occurs in various areas despite the absence of explicitly introduced defects, which may be attributed to the susceptibility of the Li ions in the local minima to the electric field. We expect that the proposed NN method can be applied to any ionic material, thereby leading to atomic-scale elucidation of ion behaviour under electric fields

“Big Data Assimilation” Toward Post-Petascale Severe Weather Prediction: An Overview and Progress

Following the invention of the telegraph, electronic computer, and remote sensing, “big data” is bringing another revolution to weather prediction. As sensor and computer technologies advance, orders of magnitude bigger data are produced by new sensors and high-precision computer simulation or “big simulation.” Data assimilation (DA) is a key to numerical weather prediction (NWP) by integrating the real-world sensor data into simulation. However, the current DA and NWP systems are not designed to handle the “big data” from next-generation sensors and big simulation. Therefore, we propose “big data assimilation” (BDA) innovation to fully utilize the big data. Since October 2013, the Japan's BDA project has been exploring revolutionary NWP at 100-m mesh refreshed every 30 s, orders of magnitude finer and faster than the current typical NWP systems, by taking advantage of the fortunate combination of next-generation technologies: the 10-petaflops K computer, phased array weather radar, and geostationary satellite Himawari-8. So far, a BDA prototype system was developed and tested with real-world retrospective local rainstorm cases. This paper summarizes the activities and progress of the BDA project, and concludes with perspectives toward the post-petascale supercomputing era.Fil: Miyoshi, Takemasa. RIKEN Advanced Institute for Computational Science; JapónFil: Lien, Guo-Yuan. RIKEN Advanced Institute for Computational Science; JapónFil: Satoh, Shinsuke. National Institute of Information and Communications Technology; JapónFil: Ushio, Tomoo. Osaka University; JapónFil: Bessho, Kotaro. Meteorological Satellite Center; JapónFil: Tomita, Hirofumi. RIKEN Advanced Institute for Computational Science; JapónFil: Nishizawa, Seiya. RIKEN Advanced Institute for Computational Science; JapónFil: Yoshida, Ryuji. RIKEN Advanced Institute for Computational Science; JapónFil: Adachi, Sachiho A.. RIKEN Advanced Institute for Computational Science; JapónFil: Liao, Jianwei. RIKEN Advanced Institute for Computational Science; JapónFil: Gerofi, Balazs. RIKEN Advanced Institute for Computational Science; JapónFil: Ishikawa, Yutaka. RIKEN Advanced Institute for Computational Science; JapónFil: Kunii, Masaru. RIKEN Advanced Institute for Computational Science; JapónFil: Ruiz, Juan Jose. RIKEN Advanced Institute for Computational Science; Japón. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maejima, Yasumitsu. RIKEN Advanced Institute for Computational Science; JapónFil: Otsuka, Shigenori. RIKEN Advanced Institute for Computational Science; JapónFil: Otsuka, Michiko. RIKEN Advanced Institute for Computational Science; JapónFil: Okamoto, Kozo. RIKEN Advanced Institute for Computational Science; JapónFil: Seko, Hiromu. Meteorological Research Institute; Japó

Quantitative PET Analysis of the Dopamine D2 Receptor Agonist Radioligand 11C-(R)-2-CH3O-N-n-Propylnorapomorphine in the Human Brain

It has been demonstrated in vitro that the dopamine D2 receptor has 2 interconvertible affinity states for endogenous dopamine, referred to as the high- and the low-affinity states. (11)C-(R)-2-CH3O-N-n-propylnorapomorphine ((11)C-MNPA) is a new agonist radioligand for in vivo imaging of the high-affinity state of dopamine D2 receptors using PET. In the present study, the kinetics of (11)C-MNPA were examined for the first time, to our knowledge, in the human brain and analyzed using quantitative approaches with or without an arterial input function. METHODS: A 90-min dynamic PET scan was obtained for 10 healthy men after an intravenous injection of (11)C-MNPA. The binding potential (BPND) was calculated using the indirect kinetic method, a kinetic compartment analysis with a metabolite-corrected arterial input function. BPND was also calculated by the simplified reference tissue model (SRTM) and transient equilibrium methods, both with the cerebellum as the reference brain region. The results of the quantitative methods were compared in a cross-validation approach. RESULTS: The highest regional radioactivity was observed in the putamen. BPND values obtained by kinetic analysis were 0.82 +/- 0.09, 0.59 +/- 0.11, and 0.28 +/- 0.06, respectively, in the putamen, caudate, and thalamus. BPND values obtained by the SRTM and transient equilibrium methods were in good agreement with those obtained by the indirect kinetic method (r = 0.98 and r = 0.93, respectively). For all quantification methods, the BPND values based on data acquired from 0 to 60 min were in good agreement with those based on data acquired from 0 to 90 min (r = 0.90-0.99). CONCLUSION: The regional distribution of (11)C-MNPA binding was in good agreement with previous PET studies of dopamine D2 receptors in the human brain using antagonist radioligands. The results support routine use of the SRTM and transient equilibrium methods, that is, methods that do not require an arterial input function and need a scan time of only about 60 min. (11)C-MNPA should thus be useful for clinical research on the pathophysiology of neuropsychiatric disorders and estimation of dopamine D2 receptor occupancy by dopaminergic drugs