In contrast to structuralists, who sought to achieve a fixed and static framework of meanings by referring concepts and content of knowledge to dominant structures and discourses, denying structures ...and meanings, post-structuralists abandoned the content of knowledge from any constraint and involved it in fluidity and ambiguities, and denied any pre-designed semantic structure. According to the post-structuralism view, there is no fixed semantic framework and no reliable foundation for knowledge, and everything is in the process of continuous decay and disintegration and every meaning is exposed to a continuous process of semantic dialectics in the dual oppositions between different and conflicting interpretations, and experiences changes, and this process continues and there is no end for it. In the field of geography, meanings are produced in the process of communication between spaces, and there are no independent meanings and identities for geographical space and place alone. According to the authors of this article, post-structuralism, despite the great noise, is a non-scientific and non-epistemic viewpoint, and before having an epistemic nature, it is considered as a political and social movement and approach. A look at the fundamentals and assumptions of this school suggests that this view has conceptual and epistemic contradictions. Relying on the claims of this school, the possibility of any scientific research, and the ability to communicate between geographic spaces and to reach the fields of interaction and dialogue between individuals, groups and spaces are lost. Therefore, the article authors' opinion is that, basically and logically, post-structuralism is something impossible, unreasonable, dimensionless, and a meaningless term.
The sociology of knowledge studies the relationship between "thought" and "society" and connects the "studied ideas" to their "socio-historical contexts"; moreover, it considers different scientific ...and professional collections of thought as the result of their cultural and social contexts. Furthermore, it is said to believe in the social determination of knowledge. This view has affected critical theories and schools in geography, and has been considered as one of the basic principles of these schools. Based on the teachings of this view, all facts and realities are social constructs and change and evolve with alteration and evolution of social structures. The current paper, which deals with the epistemological criticism on the principles and assumptions of this view, has been written in a descriptive-analytical (logical) method and critical rationalism point of view indicates that this view ultimately leads to historicism, the mix of knowledge and value, relativism, the lack of objectivity and validation of propositions and statements, and the obstruction of criticism, thus through that the obtaining scientific, valid and objective geography is not possible. In addition, by dividing the sciences into real and credits categories, it was shown that the credits in geography are of the type of rational credits (secondary philosophical concepts) and only special after-society credits that do not have an external source of abstraction (pure credits) are the result of social determination and vary from one society to another (relative). Therefore, the nature and content of geography is free from the effect of social, historical and material factors (sociology of knowledge); moreover, geography cannot be considered a social determinant.
Objective: Due to the importance of organizing space in the development of countries, governments are particularly serious about the proper division of their territorial space. The aim of this study ...is the pathology of political space management in the metropolitan city of Tehran. Methods: The present study was performed qualitatively using the data-based method and the data extracted from semi-structured interviews with 20 experts. The research was conducted in three stages of open coding, axial coding and selective coding. Foundation data method including contextual factors, causal factors, intervening factors, strategies and outcomes were identified. Results:In coding, 268 codes were first extracted and finally 60 codes were extracted from the interviews and steps were taken later. In the categories of rule of law, lack of comprehensive law, multiple management and unrest and security challenges; causal factors in the categories of extreme centralism and society and culture; Interfering factors in the categories of overcrowding and anti-corruption; Strategies were divided into the categories of the right to comment and accountability and the political participation of citizens, and consequently the categories of government effectiveness, improving the quality of regulation and political stability, and non-violence. Conclusion: In general, it can be said that the pathology of political space management in the metropolis of Tehran is very important.
Objectives: Artifacts from various dental materials are a disturbing factor which reduces the quality of images obtained from cone beam computed tomography (CBCT). This study aimed to evaluate the ...effect of tube current on dental material artifacts in CBCT imaging. To assess the amount of artifacts, signal difference to noise ratio indicator was used. Materials and Methods: In this study, twenty widely-used dental materials were used. The samples were scanned with Soredex SCANORA 3D at two different tube current of 5 and 10 mA while all other conditions remained constant. Using the On-Demand 3D Application software, the circular areas were selected as the region of interest (ROI) at 1, 2 and 4 mm from the edge of the object’s image. In each of these ROI areas, information about mean gray value was obtained and signal difference to noise ratio (SDNR) was calculated. Data regarding two scanning conditions were compared using the Wilcoxon statistical analysis. Results: Regardless of the type of material at 5 mA, SDNR at distances of 1, 2 and 4 mm were +3.6797, -1.2901, and -2.8608, respectively. SDNR at 10 mA scanning at a distance of 1, 2 and 4 mm were +3.2363, -1.1889, and -1.1844, respectively. SDNR for all materials at 5 and 10 mA scanning condition were -0.1570, and +0.2877, respectively and according to the Wilcoxon test there was significant difference (P value = 0.026). Conclusions: By varying tube current from 5 to 10 mA, SDNR index, and regardless of the type of material, the distance and direction increased. This increase reflects the reduction of artifacts from various dental materials following increase in tube current.
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