Group velocity and causality in standard relativistic resistive magnetohydrodynamics

Group velocity of electromagnetic waves in plasmas derived by standard relativistic resistive MHD (resistive RMHD) equations is superluminal. If we assume that the group velocity represents the propagation velocity of a signal, we have to worry about the causality problem. That is, some acausal phenomena may be induced, such that information transportation to the absolute past and spontaneous decrease in the entropy. Here, we tried to find the acausal phenomena using standard resistive RMHD numerical simulations in the suggested situation of the acausal phenomena. The calculation results showed that even in such situations no acausal effect happens. The numerical result with respect to the velocity limit of the information transportation is consistent with a linear theory of wave train propagation. Our results assure that we can use these equations without problems of acausal phenomena.Comment: 28 pages, 10 figure

フランスラグビーのプロ化過程と三つの主要エージェント

This article is the synthesis of a common thought with Pascal CHANTELAT and Pierre CHAIX. It presents the four great stages of the process of professionalization of French Rugby. It more particularly exposes how the managers of French Rugby face the advance of the process of professionalism initiated since the end of 1980. The arrival of new actors, in particular the National professional League of Rugby (LNR) and the Trade union of players (PROVALE), has shown the end of monopoly of the French Federation (FFR) in the management and organization of this sport. During the years 1987-2004. the changes in the definition of the rules of the game to the sporting direction (methods of organization of games) and socio-politic direction (the collective distribution of power and money), was marked by a series of hesitations and inversions of orientation, This indecision mainly arose from confrontation between the union on one side and the professional league on the other. These two organizations were mainly represented by the Presidents of the professional clubs. These entities were in conflict for controlling the "Rugby Spectacle". The analysis of the projects (talks and documents from the clubs or the union) and of the strategies from the various entities shows that this style of management reveals more about the amount of influence and opportunist strategies of alliance than that of a true governorship based on a common vision of professional Rugby, with forms of cooperation between all entities

ウォーキングとスポーツ実施の規定要因に関する文献的研究 : ウォーキング実施者の主体要因に関する特徴に着目して

This article reviews studies examining the factors that determine sports participation, focusing on the individual factors among walkers : the attitudes toward physical education, past participation in sport, and health habits. The degree of like or dislike is used most frequently to evaluate attitudes toward sport and physical activity. Sport participants tend to have a more posltive attitude toward sport activities or physical education than non-participants, and this trend is stronger among males. Moreover, the "like-dislike" attitude toward physical education has a greater influence on sports participation than same attitude toward sport. It has been suggested that, in regard to the measurement of the "like-dislike" attltude toward sport and physical education in the future, the reliability and validity of the attitude scale should be examined. Similar to "attitude toward sport", "past participation in sport" has been a major factor in studies analysing sport behaviours. It is observed that people who have belonged to a sports club and/or participated in a sport tend to engage more in sports activity. Furthermore, a person who experienced sports in a later stage of his/her life tends to participate in the sport more at the present. Sports participants acquire good health habits more than non-participants. There are, however, few studies with Japanese subjects which focus on the relationships between physical activity and other health habits. Taking into account the association of walking activity with these individual factors, it is assumed that the relationships between walking activity and "attitudes toward physical education" or "past participation in sport" are different from those between sport activity and these items : that is, a person who has a negative attitude toward physical education and did not participate in sport, tends to walk for exercise. On the other hand, health-oriented walkers would acquire more health habits than sports participants

高校野球の持つ価値と問題性に関する一考察

The main purpose of this study was to clarify by a team questionnaire the opinions of baseball players with regard to the values and problems of high school baseball. The results of this study were as follows : The total number of middle-ranked teams being greater than other teams, the replies were very numerous from these teams. On the whole, the middle-ranked teams most often sought improvements in high school baseball. Conversely, high ranking teams tended to protect their competitive situation. Low ranking teams did not give any opinions except for "surplus reaction concerning high school baseball" because they don\u27t reach at team ability which makes aware of problem and value of high shool baseball

高齢者の友人関係 : 交流館の自主グループ活動者の調査から

The purpose of this study is to clarify friendships among the elderly. A survey was conducted by questionnaires on elderly people active at a community center in Toyota City. The subjects of this study were a total of 1,901 (men=538, women=1363) elderly people over the age of sixty years. The results of this study clarified the characteristics of best friends and the structure of close friends. Characteristics of best friend were as follows: (1) a person of the same sex and ages; (2) got to know each others through a hobby or sport; (3) male friends live in the same citys; (4) female friends live in the same neighborhood. Structures close friends are characterized as follows: (1) a high rate friends of the same sex the women; (2) a low rate of friends of the same age; (3) a high rate of close friends living in the same community. A hobby and/or sports activity are important to make friends. Because their friendships developed from ways for eldery people a hobby and/or sports activity in a given neighborhood, it is suggested that such relationships may well have a certain influence upon the local community

運動行動変容の段階および運動実施に対する自己効力感の測定尺度に関する研究 : 日本語版尺度の開発と高齢者への適用

The first objective of this study was to develop a Japanese version scale of the Stages of Exercise Behavior Change and Exercise Self-Efficacy. Data for study 1 were obtained from 282 walking event participants. The validity of criteria for the scale of Stages of Exercise Behavior Change and factorial validity and reliability for the scale of Exercise Self-Efficacy were examined. The results of study 1 were as follows : 1) The higher the Stages of Exercise Behavior Change, the higher the frequency and the more practice time for exercise. 2) It became clear as a result of a confirmatory factor analysis that GFI and AGFI of 1 factor model in Exercise Self-Efficacy were at an acceptable level (GFI.976 and AGFI.927). Moreover, the Cronbach α coefficient was. 806. The second objective of this study was to examine the application of two scales developed in Study 1 for older adults. Data for Study 2 were obtained from 226 visitors over 60 years of age to an interchangeable facility for older adults. The results of Study 2 were as follows : 1) There was the similar tendency as study 1 in two scales. 2) There was no linear relationship between the Stages of Exercise Behavior Change and Exercise Self-Efficacy, as indicated in the previous study

高齢者の身体活動実施に対する社会的支援の測定尺度に関する研究

The purpose of this study was to develop a social support scale for the physical activity practice of the elderly, by examining the validity of the corresponding social support structure. Data for this study were obtained from visitors over 60 years of age to 3 facilities in the city of Fujisawa in Kanagawa Prefecture. The first step was an exploratory factor analysis to distinguish the social support structure concerning the physical activity practice of the elderly. In the second stage, a confirmatory factor analysis was performed to examine the validity of 3 models constructed from the distinguished social support structure. We found from the exploratory factor analysis that the social support structure for the physical activity practice of the elderly consisted of informational support, support concerning facilities and programs, human support and support for accessibility. Next, it became clear as a result of the confirmatory factor analysis that validity of the model in which the 4 factors have a mutual relation but are independent had a higher conformable coefficient than the other 2 models