29 research outputs found
The Role of mathematical thought in the improvement of architecture students’ abilities on logical aspects of design
Background and Objectives: Architectural education as a challengeable subject is dependent on multiple variables. Since formation of an architect character and learning design abilities are related to this subject, it is so sensitive. Historically, the role of mathematics and application of its different aspects in architectural design is indisputable. While recent decades have witnessed a high level of interaction between mathematics and architecture in the world, mathematics in architectural education in Iran is still being taught as a basic course through the lecture method. A great concern in learning architectural design is how to apply the basic courses in design process. Methods: According to the necessity of revising the role of mathematics in education of architectural design, and developing new approaches to apply mathematical thought in logical process of design, the present study aims to test an educational model in an environment consisting of test and control groups in the Basic Design 1 & 2 courses, using the proposed model of Lawson as well as quasi-experimental research method. The research subjects are selected among BA students of Islamic Azad University of Urmia (n=52). They provided logical solutions for design problems, using algebraic, arithmetic, geometric and symbolic aspects of mathematics. The subjects’ design abilities were evaluated by the performance measurement method based on verdict criteria. The researchers determined two groups of mathematical and architectural design measurement criteria. For design, the criteria included design conceptual quality, spatial and functional arrangement, form combination, presentation quality, creativity and final grade. Findings: The final grades of four research projects executed in two studios were respectively for design 62.57,66.29, 71.30, 75.31 and for mathematics 64.99, 69.27, 71.72 and 74.9. The correlation between design and mathematics evaluation scores for project 1 of the studio 1 (ƿ=0.594) and project 2 of the studio 2 (ƿ=0.604) is independently obvious which indicates the strong combination between mathematics and design aspects in these projects. For the project 2 of the studio 1, the correlation was low (ƿ= 0.166). The possible explanation could be based on the lack of real materials application and the experiment of altering theory analysis to practical analysis. The correlation between design evaluation scores and mathematics application (ƿ=0.384) reveals a positive role for mathematical thought in developing logical solutions and general quality of design. Conclusion: Findings of this study directly refers to the correspondence between research assumptions and the verdict criteria. The findings indicate that students’ performance in test group is better than the students in control group in all criteria except the presentation. The best performance by subjects of the test group means that their ability in creating solution concept has much improved compared with the control group as a result of manipulating the independent variable which is the education method in this study. This improvement couldn’t be related to other unrelated independent variables, because these variables have been either controlled or their effect has been studied through the pre-test. Stated on the findings in analyzing the general quality of design, students provided complicated geometric patterns in their design as logical, creative and efficient solutions through realizing their mathematical principles. Acquiring and developing the design schema based on design problems in the Basic design studios results the improvement of the students’ ability in logical aspects of design.  ===================================================================================== COPYRIGHTS ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers. ====================================================================================
Exendin-4 enhances the differentiation of Wharton’s jelly mesenchymal stem cells into insulin-producing cells through activation of various β-cell markers
The Relationship between Random Urinary Protein-to-Creatinine Ratio and 24-hours Urine Protein in Diagnosis of Proteinuria in Mild Preeclampsia
Background: The purpose of this study was to evaluate whether a random urinary protein / creatinine ratio is a clinically useful predictor of significant proteinuria (300 mg/24 hr) instead of 24- hours urine protein, among women with suspected preeclampsia. Methods: Women with suspected preeclampsia and gestational age of 20 weeks were included in a prospective study. Patients with chronic hypertension, diabetes mellitus, or preexisting renal disease were excluded. Protein/ creatinine ratio was obtained before 24-hours urine collection. Positive and negative predictive values and sensitivity and specificity of the protein/creatinine ratio for significant proteinuria (300 mg) were calculated, based on 24-hours urine total protein. Results: 100 women were evaluated totally. Mean maternal and gestational ages were 27.3 years and 33.26 weeks, respectively.73% of cases had significant proteinuria based on 24-hours urine collection. Good correlations were found between the protein/creatinine ratio in random urine samples and both the 24-hours urine protein excretion and the 24- hours urine protein/creatinine ratio in patients with mild preeclampsia (r=0.484, P<0.0001, and r=0.345, P<0.0001, respectively) .Receiver operator characteristic (ROC) analysis revealed an area under the curve of 0.944. The best cutoff value was of >0.18 which yields a sensitivity of 86.3%, a specificity of 100%, with a positive predictive value of 100%, and a negative predictive value of 73%. Conclusion: The random urinary protein –to- creatinine (P: C) ratio is strongly associated with the 24-hours total protein excretion. A cutoff value of > 0.18 is a good predictor of significant proteinuria .P: C ratio could replace the 24- hours urine collection as a simpler, faster, and more accurate method for the diagnosis of significant proteinuria. Key words: Preeclampsia, significant proteinuria, protein / creatinine (P: C) ratio, 24- hours urine total protein leve
Uniqueness Theorem for Lossy Anisotropic Inhomogeneous Structures with Diagonal Material Tensors
The method of transformation optics (TO) was introduced some time ago to create anisotropic inhomogeneous structures like hyper-lenses and invisibility cloaks which have diagonal material tensors. In this paper, we prove that the uniqueness theorem is valid for anisotropic inhomogeneous structures with diagonal constitutive tensors if all the tensor elements of all regions are lossy. The uniqueness theorem says for a particular sets of boundary conditions the solution to Maxwell equations are unique. The uniqueness theorem is proven for three cases: Single medium, media composed of two materials of our interest, and media composed of two materials which the one with diagonal material tensors is surrounded by the other one which could be an isotropic material. The latter case, is the one that can be considered for the TO-based materials like invisibility cloaks or hyper-lenses that have diagonal anisotropic inhomogeneous constitutive parameters. Because, the cloaks or hyper-lenses are usually surrounded by a free space and also the sources are usually outside of them
On the uniqueness of inverse electromagnetic problems for invisibility cloaks
Devices like invisibility cloaks are designed based on the method of transformation optics, which have anisotropic inhomogeneous structures. In this paper, we examine uniqueness of the inverse problem for such structures. We prove all these materials have the same surface field distribution on a surface enclosing the area of interest, while solutions to Maxwell's equations inside them are different. The uniqueness theory suggests that within the surface, the same medium should exactly be present. However, for anisotropic inhomogeneous media of our interest, this paper illustrates that this might not be true, despite the result of a previous study that shows uniqueness could be true for some anisotropic inhomogeneous structures. For the analysis, the transverse electric (TE) Z-polarization is used. The simulation results are obtained by a commercial Finite-Element based simulator
Size reduction of electromagnetic devices using double near zero materials
The phase pattern tailoring and finite/nonzero wave impedance properties of double-near-zero materials, which have both the permittivity and permeability close to zero, are utilized to reduce the size of certain electromagnetic devices. As a proof of concept, it is applied to internal and external cloaks and field concentrators. The proposed technique enables reducing the size of the investigated devices by 50% by changing their structure from a full cylinder to half cylinder. The half-sized devices can still perform the functions of their full-size counterparts. To understand the phenomenon and validate the numerical results, the method is proven analytically for the internal cloak. The same analysis can also be applied for the external cloak and concentrator. For the included analysis, the transverse electric Z-polarization is used. For the transverse magnetic Z-polarization, the duality principal can be applied
A Family of Soft-Switching DC-DC Converters with Two Degrees of Freedom
Switching losses including reverse recovery losses, have a significant impact on total losses of DC-DC converters especially in high voltage applications. This article introduces a new family of DC-DC converters with two degrees of freedom, which can handle the mentioned issue. The proposed family of DC-DC converters contains a bidirectional and a unidirectional cell, and provides an additional control parameter. This parameter can be adjusted so that there are soft switching conditions for all the switches of the converter within the entire range of loading. In addition, properly tuning the new parameter can decrease the circulating current and consequently decrease the conduction losses considerably. Besides, the unidirectional cell contributes to power transfer, especially under full load condition. Moreover, the filter capacitor is one fourth in comparison with the conventional dc-dc converters. The proposed converter is modeled and its operation modes are studied. Also, in order to verify the findings, a 500 W prototype with a frequency of 100 kHz is implemented, and the results are compared
Propranolol decreases the post-operative pain and analgesic administration following abdominal hysterectomy
Post-operative pain results in many complications. Studies suggest beta blockers to be effective in decreasing postoperative pain and analgesic requirements. This study evaluated the influence of perioperative administration of 40mg orally propranolol on patients' post-operative pain score and analgesic consumption following abdominal hysterectomy. In this double-blind randomized clinical trial, 73 women who had referred for elective abdominal hysterectomy surgery during years 2010-2011 were reviewed. Patients were randomly divided into case (receiving 40 mg orally propranolol tablet 30 min before surgery) and control (receiving orally placebo 30 min before surgery). General anesthesia was done the same for both groups. Postoperative time of first need to morphine, total morphine consumption dose and pain severity during the first 24 hours after surgery was measured among both groups. age and hysterectomy indication was not statistically different between two groups (p>0.05). Total morphine consumption in the propranolol group (2.85±2.5 mg) was lower than control group (10.35±2.2 mg) (p<0.001). The Initial morphine administration time (min) in the propranolol group was significantly longer than the control group (998.7 ± 49 vs. 261.7 ± 139.1) (p<0.001). The Pain Score (VAS scoring) (Mean±SD) in propranolol group was lower than the control group (1.03±0.58 vs. 2.76 ±0.8) (p< 0.001). administration of 40mg orally propranolol 30 minutes before abdominal hysterectomy is effective in decreasing patients' post-operative pain and morphine administration dosage. It also elongates the Initial morphine administration time in the first 24 hours following abdominal hysterectomy