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Search Results: 1 - 10 of 117892 matches for " Kohyama T "
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Sleep, Serotonin, and Suicide  [PDF]
Jun Kohyama
Journal of Behavioral and Brain Science (JBBS) , 2012, DOI: 10.4236/jbbs.2012.24055
Abstract: 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.
Capacity Limitations of Medical Services Provided by Pediatricians in Japan  [PDF]
Jun Kohyama
Open Journal of Pediatrics (OJPed) , 2014, DOI: 10.4236/ojped.2014.41014
Abstract:

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.

Dynamic change in respiratory resistance during inspiratory and expiratory phases of tidal breathing in patients with chronic obstructive pulmonary disease
Yamauchi Y, Kohyama T, Jo T, Nagase T
International Journal of Chronic Obstructive Pulmonary Disease , 2012, DOI: http://dx.doi.org/10.2147/COPD.S30399
Abstract: amic change in respiratory resistance during inspiratory and expiratory phases of tidal breathing in patients with chronic obstructive pulmonary disease Original Research (2242) Total Article Views Authors: Yamauchi Y, Kohyama T, Jo T, Nagase T Published Date April 2012 Volume 2012:7 Pages 259 - 269 DOI: http://dx.doi.org/10.2147/COPD.S30399 Received: 31 January 2012 Accepted: 04 March 2012 Published: 11 April 2012 Yasuhiro Yamauchi1,2, Tadashi Kohyama2, Taisuke Jo2, Takahide Nagase2 1Division of Health Promotion Center, 2Department of Respiratory Medicine, University of Tokyo, Tokyo, Japan Background and objective: Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation consisting of airway obstruction and parenchymal emphysema, with loss of elastic recoil. The forced oscillation technique can detect impairment of lung function by measuring lung impedance during normal tidal breathing. Respiratory resistance (Rrs) in COPD has been well-studied, but the differences in Rrs in the inspiratory and expiratory phases between mild and moderate COPD remain poorly understood. Since airway obstruction in COPD is known to change dynamically during tidal breathing and might affect Rrs, the differences in Rrs during tidal breathing between mild and moderate COPD were evaluated. Methods: Mild (n = 13) and moderate (n = 13) COPD patients were recruited at Tokyo University Hospital (Tokyo, Japan). Rrs was measured using MostGraph-01 (Chest MI, Inc, Tokyo, Japan), which depicted Rrs in a frequency- and respiratory cycle-dependent manner in three-dimensional graphics. Rrs was evaluated at 4–35 Hz during tidal breathing. Results: Rrs changed dynamically during tidal breathing in COPD. The mean Rrs values were significantly greater in the moderate COPD group than in the mild group. The maximal and minimal Rrs values at higher frequencies in the respiratory cycle were significantly greater in moderate COPD. In inspiratory–expiratory breath analysis, the maximal and minimal Rrs values at 20 Hz and 35 Hz were significantly greater in the moderate group, whereas at 4 Hz they did not differ significantly between the groups. Conclusion: Rrs changed dynamically during tidal breathing in patients with COPD. The Rrs values at higher frequencies were greater in moderate COPD than in mild COPD. Rrs at higher frequencies might reflect the degree of airway obstruction in tidal breathing in patients with COPD and might be a useful marker for evaluation of airway obstruction at an early stage of COPD.
Dynamic change in respiratory resistance during inspiratory and expiratory phases of tidal breathing in patients with chronic obstructive pulmonary disease
Yamauchi Y,Kohyama T,Jo T,Nagase T
International Journal of COPD , 2012,
Abstract: Yasuhiro Yamauchi1,2, Tadashi Kohyama2, Taisuke Jo2, Takahide Nagase21Division of Health Promotion Center, 2Department of Respiratory Medicine, University of Tokyo, Tokyo, JapanBackground and objective: Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation consisting of airway obstruction and parenchymal emphysema, with loss of elastic recoil. The forced oscillation technique can detect impairment of lung function by measuring lung impedance during normal tidal breathing. Respiratory resistance (Rrs) in COPD has been well-studied, but the differences in Rrs in the inspiratory and expiratory phases between mild and moderate COPD remain poorly understood. Since airway obstruction in COPD is known to change dynamically during tidal breathing and might affect Rrs, the differences in Rrs during tidal breathing between mild and moderate COPD were evaluated.Methods: Mild (n = 13) and moderate (n = 13) COPD patients were recruited at Tokyo University Hospital (Tokyo, Japan). Rrs was measured using MostGraph-01 (Chest MI, Inc, Tokyo, Japan), which depicted Rrs in a frequency- and respiratory cycle-dependent manner in three-dimensional graphics. Rrs was evaluated at 4–35 Hz during tidal breathing.Results: Rrs changed dynamically during tidal breathing in COPD. The mean Rrs values were significantly greater in the moderate COPD group than in the mild group. The maximal and minimal Rrs values at higher frequencies in the respiratory cycle were significantly greater in moderate COPD. In inspiratory–expiratory breath analysis, the maximal and minimal Rrs values at 20 Hz and 35 Hz were significantly greater in the moderate group, whereas at 4 Hz they did not differ significantly between the groups.Conclusion: Rrs changed dynamically during tidal breathing in patients with COPD. The Rrs values at higher frequencies were greater in moderate COPD than in mild COPD. Rrs at higher frequencies might reflect the degree of airway obstruction in tidal breathing in patients with COPD and might be a useful marker for evaluation of airway obstruction at an early stage of COPD.Keywords: COPD, airflow limitation, respiratory resistance, forced oscillation technique
Regularization parameter independent analysis in Nambu-Jona-Lasinio model
Inagaki, T.;Kimura, D.;Kohyama, H.;Kvinikhidze, A.
High Energy Physics - Phenomenology , 2013,
Abstract: Nambu-Jona-Lasinio model used to investigate low energy phenomena is nonrenormalizable, therefore the results depend on the regularization parameter in general. A possibility of the finite in four-dimensional limit and even the regularization parameter (this is dimension in the dimensional regularization scheme) independent analysis is shown in the leading order of the 1/Nc expansion.
Phase diagram of quark-antiquark and diquark condensates at finite temperature and density in the 3-dimensional Gross Neveu model
Kohyama, Hiroaki
High Energy Physics - Phenomenology , 2007, DOI: 10.1103/PhysRevD.77.045016
Abstract: We construct the phase diagrams of the quark-antiquark and diquark condensates at finite temperature and density in the 3D (dimensional) 2-flavor Gross Neveu model. We found that, in contrast to the case of the 4D Nambu Jona-Lasinio model, there is no region where the quark-antiquark and diquark condensates coexist. The phase diagrams obtained for some parameter region show similar structure with the 4D QCD phase diagram.
Early rising children are more active than late risers
Jun Kohyama
Neuropsychiatric Disease and Treatment , 2007,
Abstract: Jun KohyamaDepartment of Pediatrics, Tokyo Kita Shakai Hoken Hospital, Tokyo, JapanBackground: A low level of physical activity impacts mental as well as physical health. This study investigated the daily lifestyle habits that affect physical activity in young children.Methods: The relationship between physical activity, assessed by means of a Mini-Mitter Actiwatch device, and observed daily lifestyle habits was analyzed for 204 children, aged 12 to 40 months (average: 22.6 months), for whom 6-consecutive-day data from both the Actiwatch and sleep log were obtained.Results: An older age, male gender, and early waking time showed significant positive correlations with physical activity level. Multiple regression analysis revealed that these three variables were significant predictors of physical activity.Conclusion: Promoting an early rising time is suggested to be an important element of cultivating good health in young children.Keywords: physical activity, children, actigraphy, morning light
Effects of Pressure during Preform Densification on SiC/SiC Composites  [PDF]
Naofumi Nakazato, Akira Kohyama, Yutaka Kohno
Open Journal of Inorganic Non-metallic Materials (OJINM) , 2013, DOI: 10.4236/ojinm.2013.31003
Abstract:

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.

Analytical Study on the Sunyaev-Zeldovich Effect for Clusters of Galaxies
Satoshi Nozawa,Yasuharu Kohyama
Physics , 2009, DOI: 10.1103/PhysRevD.79.083005
Abstract: Starting from a covariant formalism of the Sunyaev-Zeldovich effect for the thermal and non-thermal distributions, we derive the frequency redistribution function identical to Wright's method assuming the smallness of the photon energy (in the Thomson limit). We also derive the redistribution function in the covariant formalism in the Thomson limit. We show that two redistribution functions are mathematically equivalent in the Thomson limit which is fully valid for the cosmic microwave background photon energies. We will also extend the formalism to the kinematical Sunyaev-Zeldovich effect. With the present formalism we will clarify the situation for the discrepancy existed in the higher order terms of the kinematical Sunyaev-Zeldovich effect.
Relativistic corrections to the Kompaneets equation
Satoshi Nozawa,Yasuharu Kohyama
Physics , 2014, DOI: 10.1016/j.astropartphys.2014.07.008
Abstract: We study the Sunyaev-Zeldovich effect for clusters of galaxies. We explore the relativistic corrections to the Kompaneets equation in terms of two different expansion approximation schemes, namely, the Fokker-Planck expansion approximation and delta function expansion approximation. We show that two expansion approximation formalisms are equivalent under the Thomson approximation, which is extremely good approximation for the CMB photon energies. This will clarify the situation for existing theoretical methods to analyse observation data.
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