In this paper an efficient method is developed for the formation of null bases of finite element models (FEMs) composed of rectangular and triangular plane stress and plane strain elements, corresponding to highly sparse and banded flexibility matrices. This is achieved by associating special graphs to the finite element models and selecting appropriate subgraphs for the formation of localized self stress systems. The efficiency of the present method is illustrated through some examples.

Different methods are used for the formation of the null basis matrix of a structure followed by calculating the element forces when the force method of structural analysis is utilized. Singular value decomposition (SVD) method is one of the algebraic methods in force method that uses equilibrium matrix in its computation of finding element forces. By increasing the dimensions of the equilibrium matrix in large scale structures, the time needed for making orthogonal matrices grows. In recent decades many researchers have worked on block-diagonalization of structural matrices such as stiffness matrix in symmetric structures to reduce the computational time and simplify the equations. Block-diagonalization of equilibrium matrix can also reduce the computational time in algebraic force methods. In this paper block-diagonalization of equilibrium matrices of circulant structure is performed using Kronocker product and SVD method is utilized to calculate the block-diagonalization null basis matrix. Finally the results are compared to those of the method without block-diagonalization and other algebraic methods.

The main part of finite element analysis via the force method involves the formation of a suitable null basis for the equilibrium matrix. For an optimal analysis, the chosen null basis matrices should exhibit sparsity and banding, aligning with the characteristics of sparse, banded, and well-conditioned flexibility matrices. In this paper, an effective method is developed for the formation of null bases of finite element models (FEMs) consisting of shell elements. This leads to highly sparse and banded flexibility matrices. This is achieved by associating specific graphs to the FEM and choosing suitable subgraphs to generate the self-equilibrating systems (SESs) on these subgraphs. The effectiveness of the present method is showcased through two examples.

To View The Abstract, Please Click On PDF File.

Background and Objectives: Rh blood group system is one of the complex systems of blood groups and composed of nearly 50 antigens. The two gens of Rh D and Rh CE are responsible for coding of Rh system. Rh null genotype does not express any of these antigens. The prevalence of phenotype Rh null is 1 person per every 6×106 individuals and it is rather difficult to find compatible blood for the recipients in need. However, as there are probably members with similar characteristics in a given family, it would be plausible to diagnose the phenotype in family members to prepare compatible blood in time of need.Case: In 2014, a 39-year-old negative female patient with hemolytic anemia referred to BoAli Hospital in Qazvin. Her sample, due to incompatibility in cross matching was further tested and her Rh null group was determined.Conclusions: This case was identified by antibody screening tests and the subsequent determination of Rh antigen phenotype. After checking other family members, her brother was identified as the second Rh null group case in the country.

Graph theoretical force methods are highly efficient for the generation of sparse and banded null bases and flexibility matrices, however, these methods require special considerations when the support conditions are indeterminate. These considerations with special methods are presented in this paper which leads to efficient utilization of graph theoretical force method for indeterminate support conditions with no substantial decrease in sparsity.

Background: Living in a university just through attending the academic environment has always been full of different experiences that play a significant and unseen role in the formation of a formal and predetermined curriculum. The purpose of this study is to narrate the seven-year lived experiences of medical students in Mashhad University of medical Sciences about the factors constituting the hidden and null forms of their curriculum. Methods: This research was conducted with the qualitative method of content analysis through 1-Semi-structured personal interview with students of different basic and clinical levels of medicine, 2-Performing two-group interviews(Focus Group) 3-Reviewing and analyzing the content of all medical students’ logbooks, the section which is about the expression of experiences, criticisms and suggestions from attending different wards of the hospital and clinical training by using Graneheim and Lundman method in data analysis. Results: After analyzing individual and group interviews as well as analyzing students' logbooks, 942 initial codes were obtained. The codes were classified in 11 main classes with the following titles: Existence of specific educational plan, content materials and educational resources, master's pattern model, student role, teaching method, assessment method, teaching and learning strategies in the environment, the role of area, location, equipment and infrastructures, teaching time, gender composition and mixing, and the atmosphere governing relationships and the environment. Conclusion: In this study the factors that formed the hidden and null experiences of medical students were examined. The students expressed their experiences and their role in learning 11 dimensions. This demonstrated that attention by politicians, policy makers, and managers can create an environment full of dynamism and education.

The formation of null basis for equilibrium matrix is the most important part of the finite element analysis when the force method is utilized. For an optimal analysis, the selected null basis matrices should be sparse and banded leading to sparse, banded and well-conditioned flexibility matrices. In this paper, an efficient algorithm is developed for the formation of null basis of triangular and rectangular plate bending finite element models, corresponding to highly sparse flexibility matrices. This is achieved by applying a modified ant colony system. An integer linear programming formulation is also presented to evaluate the quality of the results obtained by the proposed ant colony system algorithm. The efficiency of the present algorithm is illustrated through some examples.

Curriculum design is one of the main parts of the process of teaching and learning in education. In fact, the null curriculum refers to the deleted and ignored parts of a curriculum. In this study, we tried to analyze the null curriculum and identify the factors that led to the null curriculum at schools. The null curriculum occurs in three levels: Some parts of the content of textbooks are deleted or added by policy makers, writers or politicians, due to the mismatch between the needs of students and society. Some parts of the content of the curriculum are neglected by staff and teachers in schools. Finally, some parts of the content of textbooks are omitted by the students that not connected with their real life. The main objective of this research is to provide a theoretical perspective on the three levels of the null curriculum based on governing system in society, schools and students. Finally, we propose some solutions to prevent of null content in the planning or execution of curriculum.

Glaucoma is a heterogeneous group of optic neuropathies characterized by a specific pattern of optic nerve degeneration and visual field loss that is usually accompanied by increased intraocular pressure (IOP). [1] It is a major cause of irreversible blindness worldwide. [2] Primary glaucoma is classified into three major forms based on the anatomy of the anterior chamber drainage angle of the eye and the age of onset: primary congenital glaucoma (PCG), primary open angle glaucoma (POAG), and primary angle closure glaucoma (PACG). [1] In glaucoma patients with increased IOP, the increase is thought to be mainly due to impaired drainage of aqueous humor from the anterior chamber. [3]...