فهرست مطالب امین امانی

The purpose of the current research was to explain the relationship between the use of virtual space and pro-social behavior and identification of students in North Khorasan. The nature of the research is a descriptive survey type and in terms of the relationships between the variables, it was of the correlation type. The studied population of the present study were male students of the second secondary level of North Khorasan province, 384 people were selected by staged cluster sampling. To collect the data required for this research and to measure the variables of this research, three virtual world questionnaires were used by Lee et al. The validity of the questionnaires was examined and approved by the experts. The reliability of the questionnaires was calculated as (0.86), (0.80) and (0.91). The findings of the research showed that there is a significant negative relationship between the use of virtual space on prosocial behavior and students' identification. Therefore, it is suggested that schools clarify the issue of parenting and identity for families by advertising, designing brochures, holding educational classes for parents in schools and teaching the correct ways of dealing with teenagers in the media and help families in this matter.

The purpose of this study was to designing the strategic model for the development of student sport in schools in North Khorasan province. The research method is developmental and the data base method and qualitative analysis were used to realize the research goals. All of the teachers, expert teachers, and administrators of student-athletic organizations form the statistical population of the study. Due to the qualitative research, 21 people were selected as statistical sample using snowball sampling technique. Data analysis was done based on the analysis of the fundamental data theory through open, axial and selective coding. According to the results of research, human resources, financial resources, space and equipment, training and extracurricular curriculum as causal, managerial, cultural-social, media and technology factors, sport-science as contextual and financial, political, economic factors. And administrative issues were identified as intervening conditions and in various areas (structural development, managerial measures, human resource development, revenue development, space and equipment development, cultural development and development of extracurricular programs) student development strategies. The findings also showed that the development of student sport will have consequences for educational, religious, moral and educational consequences, economic and professional education, science and technology, social, biological and physical education, aesthetic and artistic. As a result, human resource development has become one of the strategies of student sport development, It is suggested to improve managers' familiarity with management skills by planning for specialized training courses and training of specialists to enter the student sports sector.

Sustainable development is an organizing principle for human life. Health is considered to be one of the basic human rights and needs and the foundation for sustainable development of societies. The purpose of this study was to investigate the relationship between health literacy and the tendency for high risk behaviors among students of North Khorasan province. This research is a descriptive correlational study. The statistical population of the study consisted of all male high school students of North Khorasan province. Using multistage cluster random sampling, 364 students were selected from 8 schools. Research tools were standard health literacy questionnaire and risk behaviors questionnaire. Data were analyzed using Pearson correlation and nonlinear regression. The reliability of the questionnaires was 0.92 and 0.87, respectively. The results showed that there is a significant relationship between health literacy and the tendency for high-risk behaviors (emotional well-being, psychological well-being and social well-being). Therefore, it is suggested that health education, health communicators, and students be provided as one of the factors promoting health information and health literacy of adolescents, courses, workshops and health education packages in relation to the prevention of mental health problems and health promotion of adolescents. Reduce social harm.

High-risk behaviors among young people are one of the most important health and social issues in today's societies that affect the individual, family and society. The purpose of this study was to investigate the relationship between using virtual networks and the tendency for high risk behaviors among the students of Maneh and Semlagh city. The survey method is used to conduct this research. The statistical population of the study consisted of all male high school students of Maneh and Somalegan who were studying in the academic year of 2017-2018. 103 students were selected from three schools using multistage cluster random sampling. The used research tools were including Keyes and Magyarmo (2003) subjective well-being questionnaire and Talebi Virtual Networks Questionnaire (2015). The data were analyzed using Pearson correlation method. Based on the analysis of the findings in the results section, the main hypothesis of the research, there is a significant relationship between the use of virtual networks and the tendency toward high-risk behaviors of students (emotional well-being, psychological well-being and social well-being), was confirmed. Therefore, it is suggested that educational workshops should be conducted on how to use virtual networks by families and cultural and educational institutions to prevent mental health problems and promote adolescent health and provide adequate information to reduce social harms.

The main purpose of this study was to investigate the effect of cyberspace on the life style of high school students in Northern Khorasan. This research is an applied research in terms of purpose and the survey method is used to conduct the research. The statistical population of the study comprises of all first and second grade students in Northern Khorasan which is considered to be 87629 people, while 398 students out of them were selected by cluster sampling method as observation unit sample. Data were collected by two questionnaires: Lifestyle (LSQ) and a researcher-made questionnaire on the positive and negative effects of social networks. The reliability of the questionnaires was assessed by using Cronbach’s alpha test for the lifestyle questionnaire (α=0.90) and for the positive and Negative social networks (α=0.94). Pearson correlation coefficient was used to test the questions. The regression test was used to determine the amount and effect of cyberspace on lifestyle. The findings of the research showed that there is a positive and significant relationship between the components of lifestyle of students and cyberspace. As a result, it is the duty of community officials to take the necessary measures in appropriate ways to strengthen the social and national identity of young people using modern technologies to help preserve and strengthen native culture and thereby contribute to national cohesion and unity.

Tobacco (Nicotianatabacum L.) is known as a model plant in tissue culture and genetic engineering from the past decades. In this study the effect of ultrasonic waves on viability and disruption of tobacco cells were investigated. For callus induction, tobacco leaf explants cultured on MS medium supplemented with 2,4-D 1.5 mg/l and 1 mg/l Kinetin. The cell suspension culture was initiated by transferring of calli into liquid medium. Then the cell suspensions exposed to ultrasonic wave with different levels of temperature and duration. Cell viability was determined by Trypan blue staining, and structural and ultra-structural disruptions in cell wall were evaluated using optical and scanning electron microscopy (SEM). The results showed that the viability of cells significantly influenced by temperature and duration of ultrasonic wave treatments. The highest cell viability (%76.702) was obtained with 2 min sonication at 25 or 40 °C, while, the highest cell wall disruption were observed at 50° C with 14 min sonication (% 18.733) and at 25° C with 20 min of ultrasonic treatment (% 17.48). Scanning electron microscopy (SEM) was confirmed the formation of different sized pores on cell wall under ultrasound treatment.

The current paper investigates the closed solution of direct kinematics of a 3-DOF translational parallel manipulator with fixed actuators called a 3-PRC TPM. This solution approach is a combination of Secant theory and Bootstrap method called Secant-Bootstrap method. This method is used for solution of nonlinear kinematics of serial robots.The advantages of this method with respect to the conventional numerical methods such as Newton-Raphson are higher accuracy, better convergence and finding of all possible solutions simultaneously. In this study, for the first time, the Secant-Bootstrap method has been used for the solution of nonlinear kinematics of translational parallel manipulator. The results of current approach show an excellent correspondence with of those traditional numerical methods such as Newton-Raphson with better convergence and higher precision of all solutions.