Efficient meta-heuristics for spacecraft trajectory optimization

190 p.Uno de los problemas más difíciles de la ingeniería espacial es la optimización de la trayectoria de las naves espaciales. Dicha optimización puede formularse como un problema de optimización que dependiendo del tipo de trayectoria, puede contener además restricciones de diversa índole. El principal objetivo de esta tesis fue el desarrollo de algoritmos metaheurísticos eficientes para la optimización de la trayectoria de las naves espaciales. Concretamente, nos hemos centrado en plantear soluciones a maniobras de naves espaciales que contemplan cambios de orbitas de largo y coto alcance. En lo que respecta a la investigación llevada a cabo, inicialmente se ha realizado una revisión de estado del arte sobre optimización de cambios de orbitas de naves espaciales. Según el estudio realizado, la optimización de trayectorias para el cambio de orbitas cuenta con cuatro claves, que incluyen la modelización matemática del problema, la definición de las funciones objetivo, el diseño del enfoque a utilizar y la obtención de la solución del problema. Una vez realizada la revisión del estado del arte, se han desarrollado dos algoritmos metaheurísticos. En primer lugar, se ha desarrollado un algoritmo evolutivo híbrido auto-adaptativo para problemas de cambio de orbitas de largo alcance y multi-impulso. El algoritmo es un método híbrido, combinado con técnicas de autoajuste y un procedimiento derefinamiento individual basado en el uso de distribuciones de probabilidad. Posteriormente, en lo que respecta a los problemas de optimización de trayectoria de los encuentros espaciales de corto alcance, se desarrolla un algoritmo de estimación de distribuciones con mecanismos de conservación de viabilidad. Los mecanismos propuestos aplican métodos innovadores de inicialización, aprendizaje y mapeo dentro del proceso de optimización. Incluyen mixturas de modelos probabilísticos, algoritmos de detección de soluciones atípicas y algunas técnicas heurísticas dentro del proceso de mapeo. Paralelamente al desarrollo de los algoritmos, se ha desarrollado un software de simulación para la visualización de los resultados obtenidos en el cambio de orbitas de las naves espaciales

Improving the growth of bovine isolated ovarian secondary follicles with Akt signaling pathway stimulation

In vitro ovarian follicle culture in females at the risk of losing fertility, such premature ovarian failure (POF) and in those subjected to chemo/radio therapy as well as in animals – species at risk of extinction in a promising strategy for fertility preservation. Development of ovarian growing follicles is regulated by the coordinated action of several signaling pathways. The use of some activators or inhibitors of signaling pathways is effective in optimizing the culture conditions of immature follicles. The aim of this study was examining in vitro growth of bovine ovarian secondary stage follicles (> 80 μm) by mimicking the process of in vivo follicular development through of the Akt signaling pathway activator, PS48. Small secondary stage follicles were isolated by enzymatic digestion from slaughter ovaries by collagenase type I and Dnase I, cultured in the presence of BSA (3 mg/ml), FBS (10%), Akt (5µM PS48, first 48 h of culture) or Akt + FBS (5µM PS48, first 48 h of culture + 10% FBS) for ten days and then evaluated for growth rate. The follicular size was significantly increased in all experimental groups during 10 days culture (P<0.05). In all our groups, growth rate/day was higher in initial days of culture, after that follicular growth rate decreased. The highest growth rate was observed in FBS + PS48 group, while the lowest growth rate was detected in PS48. On the other hand, though the FBS supplemented group could increase the growth rate of follicles, its combination with PS48 was more effective . In conclusion, in our study condition the best result in follicular growth, was obtained when follicular culture medium was supplemented with FBS + PS48. In conclusion, in our study condition the best result in follicular growth, was obtained when follicular culture medium was supplemented with FBS + PS48. Keywords: Cattle, In vitro culture, Secondary Follicles, Akt signaling pathway, PS4

Modeling borderline personality symptoms based on attachment: the mediating role of self-differentiation and mentalization

Background and Aim: Borderline personality disorder is a complex and serious mental disorder that is characterized by a pervasive pattern of problems in regulating emotions and controlling impulses, and instability in interpersonal relationships and self-concept. The aim of the present study was to model borderline personality symptoms based on attachment: the mediating role of self-differentiation and mentalization. Methods: The current research is descriptive and correlational (using structural equation modeling). The statistical population studied in this research included all the female and male students of the undergraduate and postgraduate courses of Tehran Azad University who were studying in the academic year 2019-20. The sample of the present study included 370 people who were selected by purposive sampling. Data were collected using the Borderline Personality Questionnaire (Lishnernig, 1999), the Revised Close Relationships-Relationship Structure Questionnaire (Fraley, Valero Brennan, 2000), the Self-Differentiation Questionnaire of Skorn and Friedlander (1998) and the Reflective Action Scale of Fonagy et al. 2015) was obtained. In the present study, the mean, standard deviation, correlation and normality of the distribution of research variables were investigated using descriptive statistics. Also, in order to analyze the data and answer the research questions, the structural equation modeling method is used, which after confirmatory factor analysis - in the measurement model part, in the structural equation model part, the existing causal relationships between the variables are examined. In the part of the structural function model, the intensity of the causal relationships (direct, indirect and total) between the underlying variables and the amount of variance explained in the whole model is specified. SPSS and Amos version 21 software were used for this purpose. Results: The results showed that attachment (β=0.41), self-differentiation (β=0.24), and mentalization (β=0.28) have a direct effect on borderline personality symptoms (P<0.001). Self-differentiation and mentalization had a mediating role in the relationship between borderline personality symptoms and attachment. Conclusion: As a result, it can be concluded that the modeling of borderline personality symptoms based on attachment with the mediating role of self-differentiation, and mentalization has a favorable fit

Male Pronuclear Formation using Dog Sperm Derived from Ectopic Testicular Xenografts, Testis, and Epididymis

Abstract Background: Testis tissue xenografting and the resultant sperm in a xenograft may provide a unique approach to rescue the genetic material of males that die prematurely and is a model for the study of human spermatogenesis and can represent an alternative approach for fertility preservation in cancer patients. This study was aimed to evaluate the xenogenic dog sperm in formation of male pronucleus following injection into the sheep oocytes

A Study on the Relationship between Quality of Work Life and Job Enrichment among Electricity Operators

Introduction and Purpose: Job enrichment is one of the modes of improving the&nbsp;employees&rsquo; quality of work life, that if properly done, the employees will enjoy high&nbsp;quality of work life. Therefore, the current study aimed to investigate the relationship&nbsp;between quality of work life and job enrichment among electricity operators in&nbsp;Markazi Province in 2015.Methods: This study is cross-sectional and practical. The population under&nbsp;investigation corresponds to a group of 80 electric power transmission operators in&nbsp;Markazi Province, who were selected through stratified random sampling from a set&nbsp;of positions available in three areas of the province. For the purpose of measuring&nbsp;the employees&rsquo; quality of working life and job enrichment, Van Laar and Hackman&nbsp;and Oldham questionnaires were used, respectively. Data analysis was performed by&nbsp;using descriptive statistics, chi-square test, and Fisher's exact test, using SPSS 22.&nbsp;Results: The results of the study demonstrated that electricity operators enjoyed&nbsp;average job enrichment with the mean score of 54.3% and also average quality of&nbsp;working life with the mean score of 54.48%. Moreover, this study revealed a direct&nbsp;and significant correlation between the job enrichment and quality of working life.Conclusion: Due to the low level of job enrichment and quality of work life among&nbsp;the operators, the current study highlighted the role of management in implementing&nbsp;effective interventions to improve these two mediums