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A Proposal on the Novel Method to Estimate Optimal Sleep Duration Based on Self-Reported Survey Data

Journal of Behavioral and Brain Science 2024年第8期14卷 227-239页

作者： Jun kohyama Department of Pediatrics Tokyo Bay Urayasu Ichikawa Medical Center Chiba Japan

Background: Many adolescents have a sleep debt. Individuals sleeping for their optimal sleep duration are expected to experience no sleepiness. Then, it is important to recognize one’s optimal sleep duration to reduce sleep debt. However, there is no simple method to determine this value. Since body mass index and sleep duration exhibit a U-shaped association, it is expected that a person taking optimal sleep duration would show no marked deviation from the mean body mass index value for the population evaluated. By using self-reported sleepiness and standardized body mass index, this study aimed to estimate individual optimal sleep duration. Methods: Data from 2540 grade 5 - 11 students were used. Students who declared no sleepiness during class and also had a gender- and grade-standardized body mass index of ±1.5 were termed ideal students. The average sleep durations of ideal students were compared with those of non-ideal students. The differences of sleep duration between ideal and no-ideal students were added to habitual sleep duration of each non-ideal student to obtain assumed optimal sleep duration. A multiple regression line to predict assumed optimal sleep duration was calculated using the least squares method. Results: The mean sleep duration of 666 ideal students exceeded the lower limit of daily sleep duration proposed as “may be appropriate” for children aged 6 - 17 years by National Sleep Foundation of the USA, being longer than those of non-ideal students. Significant regression formula for assumed optimal sleep duration was obtained (adjusted R2 = 0.996, p Conclusions: No contradiction was identified in the sleep duration obtained from ideal students as with optimal sleep duration. Although further studies to confirm the current estimation are needed, a simple formula to estimate individual optimal sleep duration through easily obtainable parameters was proposed.

关键词： Body Mass Index Catch-Up Sleep Insufficient Sleep Syndrome Optimal Sleep Duration Sleepiness

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Understanding of the activity difference between nanogold and bulk gold by relativistic effects

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Journal of Energy Chemistry 2015年第4期24卷 485-489页

作者： Keju Sun Masanori kohyama Shingo Tanaka Seiji Takeda The Institute of Scientific and Industrial Research Osaka University Research Institute for Ubiquitous Energy Devices National Institute of Advanced Industrial Science and Technology (AIST)

It is a challenge to thoroughly understand the astonishing difference in catalytic activity between nanogold and bulk gold for some oxidation reactions. In this work,the Au–O interactions in various surroundings were investigated by DFT calculations and compared with the Ag–O interactions. We have found the three ***,only Au–O bond can be significantly strengthened by the linear O–Au–O structure. Second,the Au–O bond is always stronger than the Ag–O bond when the bonds are embedded in common surroundings. Third,the Au–O bond becomes weaker than the Ag–O bond when the number of neighboring Au atoms becomes large,because the Au–O interactions are suppressed by the presence of neighboring gold atoms. The origin of these three points can be attributed to wider spatial extension of d orbitals of gold,induced by strong relativistic effects. The strong relativistic effects make nanogold with smaller coordinate numbers highly active due to the ease in forming strong Au–O bonds,especially for the O–Au–O bond,whereas gold atoms in bulk with larger coordination numbers chemically inert due to the strong suppression by neighboring gold atoms destabilizing the O–Au–O bond.

关键词： Nanogold Au–O interactions Relativistic effects DFT calculations

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Recent Progresses and Critical Issues of SiC_f/SiC Composite Under Irradiation Environments

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Plasma Science and Technology 2003年第5期5卷 1965-1976页

作者：沙建军 A.kohyama Y.Katoh Graduate School of Energy Science Kyoto UniversityGokashoUjiKyoto 611-0011Japan Institute of Advanced Energy Kyoto UniversityGokashoUjiKyoto 611-0011 Japan

SiC with fiber-reinforced composites, which are presently considered as the primary structural materials in some fusion reactor conceptual designs, are more attractive and competitive for structural materials in a fusion energy system because of its excellent chemical and mechanical properties such as high fracture toughness, induced-low activation, afterheat under 14MeV neutron irradiation environment at elevated temperature, and good compatibility with coolant and breeder materials. Thus it is important to investigate the research progress of advanced SiC composite, including transmuted helium gas, radiation swelling, radiation effects on mechanical properties, irradiation-enhanced creep, fatigue, physical properties associated with fusion design and their critical issues. This report summarized these results and addressed the major critical issues under irradiation conditions.

关键词： SiCf/SiC composite irradiation environments

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Environmental Effects on Microstructural Stability of SiC/SiC Composites

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 125-128页

作者： Shibayama T. He G.W. Takahashi H. Katoh Y. kohyama A. Center for Advanced Research of Energy Technology Hokkaido University Sapporo 060-8628 Japan Institute of Advanced Energy Kyoto University Gokasho Uji 611-0011 Japan

LowZmaterialshavemanyadvantagesinnuclearenvirOInnellts,suchaslessProductionofradioactivewastesduetosubstantiallylowactivation,andhigherconVergentefficiencyduetothecapabilityofhightemp;***-basedmaterialsforfhaionreacto... 详细信息

关键词： ceramic matrix composite SiC oxidation crystallization interface

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Sleep, Serotonin, and Suicide

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Journal of Behavioral and Brain Science 2012年第4期2卷 471-478页

作者： Jun kohyama Tokyo Bay Urayasu/Ichikawa Medical Center Urayasu Japan

The author hypothesizes that sleep loss associated with a decrease in serotonergic activity plays a significant role in attempted suicide. Recent research has emphasized the role of the economic recession on the occurrence of suicide, but with no attention paid to possible biological aspects. In this brief review, the association between sleep, the serotonergic system, and suicide is initially introduced. Then, with consideration of recent research, a hypothesis regarding the oc- currence of suicide is proposed. Finally, based on that hypothesis, three factors possibly germane to reducing suicides (sufficient sleep duration, activation of the serotonergic system, and activation of the prefrontal cortex) are discussed.

关键词： Economic Crisis Prefrontal Cortex C-Fiber Yomikikase Dakko

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Non-School Day Catch-Up Sleep among Pupils in Japan

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Journal of Behavioral and Brain Science 2023年第6期13卷 113-125页

作者： Jun kohyama Tokyo Bay Urayasu/Ichikawa Medical Center Urayasu Japan

Backgrounds: Weekend catch-up sleep is the difference in sleep duration between the weekend and weekdays, and reflects sleep debt, whose significance is hypothesized to be altered by weekday sleep duration. This study aimed to assess this hypothesis. Methods: Multiple-comparison tests and multiple-regression analyses were conducted on questionnaires asking various lifestyle habits obtained from 2722 pupils in grades 5 to 12 and stratified by groups of pupils with shorter (≤7 hours) or longer (>7 hours) sleep duration on the nights before schooldays. Results: The percentage of pupils in negative non-school day catch-up sleep category was 6.6%, whereas that in non-school day catch-up sleep > 2 hours was 14.4%. In comparison with the reference category (non-school day catch-up sleep of zero), multiple comparison tests on lifestyle habits revealed significantly longer screen time in the shorter sleep-duration group of pupils with negative non-school day catch-up sleep and those with non-school day catch-up sleep > 2 hours. This analysis also demonstrated a significantly longer screen time in the longer sleep-duration group of pupils with non-school day catch-up sleep > 2 hours. Physical activity in pupils with negative non-school day catch-up sleep in the longer sleep-duration group was significantly longer, while that in pupils with non-school day catch-up sleep > 2 hours in the shorter sleep-duration group was significantly shorter. In the longer sleep-duration group, pupils with non-school day catch-up sleep > 2 hours showed poorer academic performance. Multiple regression analysis revealed that longer physical and after-school activities were significantly associated with non-school day catch-up sleep decrease in both the study groups. In the longer sleep-duration group, male gender, shorter screen time, and higher standardized body mass index were significantly associated with decreased non-school day catch-up sleep. Conclusions: Sleep duration before school days c

关键词： Academic Performance Body Mass Index Physical Activity After-School Activity Screen Time

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Determinants of Sleepiness among Pupils in Kanto District of Japan

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Journal of Behavioral and Brain Science 2021年第5期11卷 97-106页

作者： Jun kohyama Department of Paediatrics Tokyo Bay Urayasu Ichikawa Medical Centre Urayasu Japan

Backgrounds: Sleepiness is reported to predict sleep quality, academic performance and self-regulation. This study aimed to discover determinants of sleepiness. Methods: On 2722 questionnaires obtained from pupils in grades 5 - 12 in the Kanto district of Japan, lifestyle habits associated with sleepiness were analyzed using a multivariable logistic regression model. Results: The rate of sleepy pupils (who feel sleepy during class as often and always) increased from elementary school (6.3%) to senior high school (42.4%) via junior high school (17.1%). Higher grade (adjusted odds ratio [OR], 1.28;95% confidence interval [CI], 1.21 - 1.37;p Conclusions: To reduce adolescents’ sleepiness in the Kanto district of Japan, we recommend them to have adequate waking time, and to avoid late bedtime, breakfast skipping, excessive screen time, after-school activity, and physical activity. Further prospective studies are needed to confirm involvements of these recommended factors in sleepiness and both physical and mental health outcomes.

关键词： Academic Performance After-School Activity Bedtime Breakfast Skipping Physical Activity Screen Time Wake Time

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Mechanical properties of Fe-rich Si alloy from Hamiltonian

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npj Computational Materials 2017年第1期3卷 391-404页

作者： Tetsuo Mohri Ying Chen Masanori kohyama Shigenobu Ogata Arkapol Saengdeejing Somesh Kumar Bhattacharya Masato Wakeda Shuhei Shinzato Hajime Kimizuka Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Fracture and Reliability Research Institute School of EngineeringTohoku UniversitySendai 980-8579Japan Research Institute of Electrochemical Energy Department of Energy and EnvironmentNational Institute of Advanced Industrial Science and TechnologyIkedaOsaka 563-8577Japan Department of Mechanical Science and Bioengineering Osaka UniversityOsaka 560-8531Japan Center for Elements Strategy Initiative for Structural Materials Kyoto UniversityKyoto 606-8501Japan Computational Structural Materials Design Group Research Center for Structural MaterialsNational Institute for Materials ScienceTsukuba 305-0047Japan

The physical origins of the mechanical properties of Fe-rich Si alloys are investigated by combining electronic structure calculations with statistical mechanics means such as the cluster variation method,molecular dynamics simulation,etc,applied to homogeneous and heterogeneous ***,we examined the elastic properties based on electronic structure calculations in a homogeneous system and attributed the physical origin of the loss of ductility with increasing Si content to the combined effects of magneto-volume and D03 *** a typical example of a heterogeneity forming a microstructure,we focus on grain boundaries,and segregation behavior of Si atoms is studied through high-precision electronic structure *** kinds of segregation sites are identified:looser and tighter *** on the site,different segregation mechanisms are ***,the dislocation behavior in the Fe-Si alloy is investigated mainly by molecular dynamics simulations combined with electronic structure *** solid-solution hardening and softening are interpreted in terms of two kinds of energy barriers for kink nucleation and migration on a screw dislocation ***,the clue to the peculiar work hardening behavior is discussed based on kinetic Monte Carlo simulations by focusing on the preferential selection of slip planes triggered by kink nucleation.

关键词： alloy softening microstructure

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Capacity Limitations of Medical Services Provided by Pediatricians in Japan

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Open Journal of Pediatrics 2014年第1期4卷 102-106页

作者： Jun kohyama Tokyo Bay Urayasu Ichikawa Medical Center Urayasu Japan

The shortage of pediatricians has been identified as one of the largest social problems in Japan. This study aimed to compare the assumed ideal nighttime working conditions of pediatric hospitalists in Japan with the actual current situation. By using available data on the age-related numbers of pediatricians in Japan, we described the ideal working conditions for pediatric hospitalists in Japan. The ideal situation was then compared with the existing actual working conditions. Compared with the assumed ideal condition, current pediatric hospitalists are working in many hospitals with a few colleagues. To solve the current supply-demand mismatch on medical care for children during night, an involvement of non-pediatric physicians in the medical care of children during the night is indispensable. Also, parents in Japan need to know the limitations relating to the available capacity of pediatricians, and accept that their children can be cared for adequately by non-pediatric physicians, who have been trained to provide primary medical care to children.

关键词： Pediatric Hospitalist Night-Duty Social Needs Non-Pediatric Physician Parents

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Effects of Pressure during Preform Densification on SiC/SiC Composites

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Open Journal of Inorganic Non 2013年第1期3卷 10-13页

作者： Naofumi Nakazato Akira kohyama Yutaka Kohno College of Design and Manufacturing Technology Muroran Institute of Technology Muroran Japan Graduate School of Chemical and Materials Engineering Muroran Institute of Technology Muroran Japan Organization of Advanced Sustainability Initiative for Energy System/Materials (OASIS) Muroran Institute of Technology Muroran Japan

The nano-infiltration and transient eutectic-phase (NITE) method is one of the most attractive methods for fabrication of SiC and SiC/SiC composites. In the NITE method, preform densification is essential option for damage less near-net shaping technique. However, optimization of preform densification is insufficient yet. The objective of this study is to evaluate the effects of pressure during preform densification on SiC/SiC composites. The preform before preform densification has many pores in the inter-prepreg sheets. These pores were disappeared by preform densification. As the effects of pressure on preform, densification in the intra-fiber-bundle was improved due to increasing pressure. Flexural strength of the preforms with 1 MPa and 17 MPa indicated almost same value. The result suggested that increasing of pressure did not cause any change in fiber properties. In the effects of pressure on the composites, the composites with 17 MPa was exhibited improvement in bulk density and mechanical property, compared with that with 1 MPa.

关键词： SiC/SiC Composites NITE Method Near-Net Shaping Preform Densification

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